Bump version to 5.1.13 for release

* Add 1.21.8 to supported versions
* Correct resource pack version range

.editorconfig

@@ -0,0 +1,491 @@
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 2
+indent_style = space
+insert_final_newline = false
+max_line_length = 120
+tab_width = 2
+ij_continuation_indent_size = 4
+ij_formatter_off_tag = @formatter:off
+ij_formatter_on_tag = @formatter:on
+ij_formatter_tags_enabled = true
+ij_smart_tabs = false
+ij_visual_guides = 
+ij_wrap_on_typing = false
+
+[*.java]
+ij_smart_tabs = true
+ij_java_align_consecutive_assignments = false
+ij_java_align_consecutive_variable_declarations = false
+ij_java_align_group_field_declarations = false
+ij_java_align_multiline_annotation_parameters = false
+ij_java_align_multiline_array_initializer_expression = false
+ij_java_align_multiline_assignment = false
+ij_java_align_multiline_binary_operation = false
+ij_java_align_multiline_chained_methods = false
+ij_java_align_multiline_deconstruction_list_components = true
+ij_java_align_multiline_extends_list = false
+ij_java_align_multiline_for = true
+ij_java_align_multiline_method_parentheses = false
+ij_java_align_multiline_parameters = false
+ij_java_align_multiline_parameters_in_calls = false
+ij_java_align_multiline_parenthesized_expression = false
+ij_java_align_multiline_records = true
+ij_java_align_multiline_resources = true
+ij_java_align_multiline_ternary_operation = false
+ij_java_align_multiline_text_blocks = false
+ij_java_align_multiline_throws_list = false
+ij_java_align_subsequent_simple_methods = false
+ij_java_align_throws_keyword = false
+ij_java_align_types_in_multi_catch = true
+ij_java_annotation_parameter_wrap = off
+ij_java_array_initializer_new_line_after_left_brace = false
+ij_java_array_initializer_right_brace_on_new_line = true
+ij_java_array_initializer_wrap = off
+ij_java_assert_statement_colon_on_next_line = false
+ij_java_assert_statement_wrap = off
+ij_java_assignment_wrap = off
+ij_java_binary_operation_sign_on_next_line = false
+ij_java_binary_operation_wrap = off
+ij_java_blank_lines_after_anonymous_class_header = 0
+ij_java_blank_lines_after_class_header = 0
+ij_java_blank_lines_after_imports = 1
+ij_java_blank_lines_after_package = 1
+ij_java_blank_lines_around_class = 1
+ij_java_blank_lines_around_field = 0
+ij_java_blank_lines_around_field_in_interface = 0
+ij_java_blank_lines_around_field_with_annotations = 0
+ij_java_blank_lines_around_initializer = 1
+ij_java_blank_lines_around_method = 1
+ij_java_blank_lines_around_method_in_interface = 1
+ij_java_blank_lines_before_class_end = 1
+ij_java_blank_lines_before_imports = 1
+ij_java_blank_lines_before_method_body = 0
+ij_java_blank_lines_before_package = 0
+ij_java_block_brace_style = end_of_line
+ij_java_block_comment_add_space = false
+ij_java_block_comment_at_first_column = true
+ij_java_builder_methods = 
+ij_java_call_parameters_new_line_after_left_paren = false
+ij_java_call_parameters_right_paren_on_new_line = true
+ij_java_call_parameters_wrap = off
+ij_java_case_statement_on_separate_line = true
+ij_java_catch_on_new_line = false
+ij_java_class_annotation_wrap = split_into_lines
+ij_java_class_brace_style = end_of_line
+ij_java_class_count_to_use_import_on_demand = 1000
+ij_java_class_names_in_javadoc = 1
+ij_java_deconstruction_list_wrap = normal
+ij_java_do_not_indent_top_level_class_members = false
+ij_java_do_not_wrap_after_single_annotation = false
+ij_java_do_not_wrap_after_single_annotation_in_parameter = false
+ij_java_do_while_brace_force = never
+ij_java_doc_add_blank_line_after_description = true
+ij_java_doc_add_blank_line_after_param_comments = false
+ij_java_doc_add_blank_line_after_return = false
+ij_java_doc_add_p_tag_on_empty_lines = true
+ij_java_doc_align_exception_comments = false
+ij_java_doc_align_param_comments = false
+ij_java_doc_do_not_wrap_if_one_line = false
+ij_java_doc_enable_formatting = true
+ij_java_doc_enable_leading_asterisks = true
+ij_java_doc_indent_on_continuation = false
+ij_java_doc_keep_empty_lines = true
+ij_java_doc_keep_empty_parameter_tag = true
+ij_java_doc_keep_empty_return_tag = true
+ij_java_doc_keep_empty_throws_tag = true
+ij_java_doc_keep_invalid_tags = true
+ij_java_doc_param_description_on_new_line = false
+ij_java_doc_preserve_line_breaks = false
+ij_java_doc_use_throws_not_exception_tag = true
+ij_java_else_on_new_line = false
+ij_java_enum_constants_wrap = off
+ij_java_enum_field_annotation_wrap = off
+ij_java_extends_keyword_wrap = off
+ij_java_extends_list_wrap = off
+ij_java_field_annotation_wrap = split_into_lines
+ij_java_field_name_prefix = 
+ij_java_field_name_suffix = 
+ij_java_finally_on_new_line = false
+ij_java_for_brace_force = never
+ij_java_for_statement_new_line_after_left_paren = false
+ij_java_for_statement_right_paren_on_new_line = true
+ij_java_for_statement_wrap = off
+ij_java_generate_final_locals = false
+ij_java_generate_final_parameters = false
+ij_java_generate_use_type_annotation_before_type = true
+ij_java_if_brace_force = never
+ij_java_imports_layout = @*,*,|,java.**,|,$*
+ij_java_indent_case_from_switch = true
+ij_java_insert_inner_class_imports = false
+ij_java_insert_override_annotation = true
+ij_java_keep_blank_lines_before_right_brace = 2
+ij_java_keep_blank_lines_between_package_declaration_and_header = 2
+ij_java_keep_blank_lines_in_code = 2
+ij_java_keep_blank_lines_in_declarations = 2
+ij_java_keep_builder_methods_indents = false
+ij_java_keep_control_statement_in_one_line = true
+ij_java_keep_first_column_comment = true
+ij_java_keep_indents_on_empty_lines = false
+ij_java_keep_line_breaks = true
+ij_java_keep_multiple_expressions_in_one_line = false
+ij_java_keep_simple_blocks_in_one_line = false
+ij_java_keep_simple_classes_in_one_line = true
+ij_java_keep_simple_lambdas_in_one_line = false
+ij_java_keep_simple_methods_in_one_line = false
+ij_java_label_indent_absolute = false
+ij_java_label_indent_size = 0
+ij_java_lambda_brace_style = end_of_line
+ij_java_layout_on_demand_import_from_same_package_first = true
+ij_java_layout_static_imports_separately = true
+ij_java_line_comment_add_space = false
+ij_java_line_comment_add_space_on_reformat = false
+ij_java_line_comment_at_first_column = true
+ij_java_local_variable_name_prefix = 
+ij_java_local_variable_name_suffix = 
+ij_java_method_annotation_wrap = split_into_lines
+ij_java_method_brace_style = end_of_line
+ij_java_method_call_chain_wrap = off
+ij_java_method_parameters_new_line_after_left_paren = true
+ij_java_method_parameters_right_paren_on_new_line = true
+ij_java_method_parameters_wrap = on_every_item
+ij_java_modifier_list_wrap = false
+ij_java_multi_catch_types_wrap = normal
+ij_java_names_count_to_use_import_on_demand = 10
+ij_java_new_line_after_lparen_in_annotation = false
+ij_java_new_line_after_lparen_in_deconstruction_pattern = true
+ij_java_new_line_after_lparen_in_record_header = false
+ij_java_new_line_when_body_is_presented = false
+ij_java_packages_to_use_import_on_demand = 
+ij_java_parameter_annotation_wrap = off
+ij_java_parameter_name_prefix = 
+ij_java_parameter_name_suffix = 
+ij_java_parentheses_expression_new_line_after_left_paren = false
+ij_java_parentheses_expression_right_paren_on_new_line = true
+ij_java_place_assignment_sign_on_next_line = false
+ij_java_prefer_longer_names = true
+ij_java_prefer_parameters_wrap = false
+ij_java_preserve_module_imports = true
+ij_java_record_components_wrap = normal
+ij_java_repeat_synchronized = true
+ij_java_replace_instanceof_and_cast = true
+ij_java_replace_null_check = true
+ij_java_replace_sum_lambda_with_method_ref = true
+ij_java_resource_list_new_line_after_left_paren = false
+ij_java_resource_list_right_paren_on_new_line = true
+ij_java_resource_list_wrap = off
+ij_java_rparen_on_new_line_in_annotation = true
+ij_java_rparen_on_new_line_in_deconstruction_pattern = true
+ij_java_rparen_on_new_line_in_record_header = true
+ij_java_space_after_closing_angle_bracket_in_type_argument = false
+ij_java_space_after_colon = true
+ij_java_space_after_comma = true
+ij_java_space_after_comma_in_type_arguments = true
+ij_java_space_after_for_semicolon = true
+ij_java_space_after_quest = true
+ij_java_space_after_type_cast = true
+ij_java_space_before_annotation_array_initializer_left_brace = false
+ij_java_space_before_annotation_parameter_list = false
+ij_java_space_before_array_initializer_left_brace = false
+ij_java_space_before_catch_keyword = true
+ij_java_space_before_catch_left_brace = true
+ij_java_space_before_catch_parentheses = true
+ij_java_space_before_class_left_brace = true
+ij_java_space_before_colon = true
+ij_java_space_before_colon_in_foreach = true
+ij_java_space_before_comma = false
+ij_java_space_before_deconstruction_list = false
+ij_java_space_before_do_left_brace = true
+ij_java_space_before_else_keyword = true
+ij_java_space_before_else_left_brace = true
+ij_java_space_before_finally_keyword = true
+ij_java_space_before_finally_left_brace = true
+ij_java_space_before_for_left_brace = true
+ij_java_space_before_for_parentheses = true
+ij_java_space_before_for_semicolon = false
+ij_java_space_before_if_left_brace = true
+ij_java_space_before_if_parentheses = true
+ij_java_space_before_method_call_parentheses = false
+ij_java_space_before_method_left_brace = true
+ij_java_space_before_method_parentheses = false
+ij_java_space_before_opening_angle_bracket_in_type_parameter = false
+ij_java_space_before_quest = true
+ij_java_space_before_switch_left_brace = true
+ij_java_space_before_switch_parentheses = true
+ij_java_space_before_synchronized_left_brace = true
+ij_java_space_before_synchronized_parentheses = true
+ij_java_space_before_try_left_brace = true
+ij_java_space_before_try_parentheses = true
+ij_java_space_before_type_parameter_list = false
+ij_java_space_before_while_keyword = true
+ij_java_space_before_while_left_brace = true
+ij_java_space_before_while_parentheses = true
+ij_java_space_inside_one_line_enum_braces = false
+ij_java_space_within_empty_array_initializer_braces = false
+ij_java_space_within_empty_method_call_parentheses = false
+ij_java_space_within_empty_method_parentheses = false
+ij_java_spaces_around_additive_operators = true
+ij_java_spaces_around_annotation_eq = true
+ij_java_spaces_around_assignment_operators = true
+ij_java_spaces_around_bitwise_operators = true
+ij_java_spaces_around_equality_operators = true
+ij_java_spaces_around_lambda_arrow = true
+ij_java_spaces_around_logical_operators = true
+ij_java_spaces_around_method_ref_dbl_colon = false
+ij_java_spaces_around_multiplicative_operators = true
+ij_java_spaces_around_relational_operators = true
+ij_java_spaces_around_shift_operators = true
+ij_java_spaces_around_type_bounds_in_type_parameters = true
+ij_java_spaces_around_unary_operator = false
+ij_java_spaces_inside_block_braces_when_body_is_present = false
+ij_java_spaces_within_angle_brackets = false
+ij_java_spaces_within_annotation_parentheses = false
+ij_java_spaces_within_array_initializer_braces = false
+ij_java_spaces_within_braces = false
+ij_java_spaces_within_brackets = false
+ij_java_spaces_within_cast_parentheses = false
+ij_java_spaces_within_catch_parentheses = false
+ij_java_spaces_within_deconstruction_list = false
+ij_java_spaces_within_for_parentheses = false
+ij_java_spaces_within_if_parentheses = false
+ij_java_spaces_within_method_call_parentheses = false
+ij_java_spaces_within_method_parentheses = false
+ij_java_spaces_within_parentheses = false
+ij_java_spaces_within_record_header = false
+ij_java_spaces_within_switch_parentheses = false
+ij_java_spaces_within_synchronized_parentheses = false
+ij_java_spaces_within_try_parentheses = false
+ij_java_spaces_within_while_parentheses = false
+ij_java_special_else_if_treatment = true
+ij_java_static_field_name_prefix = 
+ij_java_static_field_name_suffix = 
+ij_java_subclass_name_prefix = 
+ij_java_subclass_name_suffix = Impl
+ij_java_switch_expressions_wrap = normal
+ij_java_ternary_operation_signs_on_next_line = false
+ij_java_ternary_operation_wrap = off
+ij_java_test_name_prefix = 
+ij_java_test_name_suffix = Test
+ij_java_throws_keyword_wrap = off
+ij_java_throws_list_wrap = off
+ij_java_use_external_annotations = false
+ij_java_use_fq_class_names = false
+ij_java_use_relative_indents = false
+ij_java_use_single_class_imports = true
+ij_java_variable_annotation_wrap = off
+ij_java_visibility = public
+ij_java_while_brace_force = never
+ij_java_while_on_new_line = false
+ij_java_wrap_comments = false
+ij_java_wrap_first_method_in_call_chain = false
+ij_java_wrap_long_lines = false
+ij_java_wrap_semicolon_after_call_chain = false
+
+[*.properties]
+ij_properties_align_group_field_declarations = false
+ij_properties_keep_blank_lines = false
+ij_properties_key_value_delimiter = equals
+ij_properties_spaces_around_key_value_delimiter = false
+
+[.editorconfig]
+ij_editorconfig_align_group_field_declarations = false
+ij_editorconfig_space_after_colon = false
+ij_editorconfig_space_after_comma = true
+ij_editorconfig_space_before_colon = false
+ij_editorconfig_space_before_comma = false
+ij_editorconfig_spaces_around_assignment_operators = true
+
+[{*.ant,*.fxml,*.jhm,*.jnlp,*.jrxml,*.jspx,*.pom,*.rng,*.tagx,*.tld,*.wsdl,*.xml,*.xsd,*.xsl,*.xslt,*.xul}]
+ij_xml_align_attributes = true
+ij_xml_align_text = false
+ij_xml_attribute_wrap = normal
+ij_xml_block_comment_add_space = false
+ij_xml_block_comment_at_first_column = true
+ij_xml_keep_blank_lines = 2
+ij_xml_keep_indents_on_empty_lines = false
+ij_xml_keep_line_breaks = true
+ij_xml_keep_line_breaks_in_text = true
+ij_xml_keep_whitespaces = false
+ij_xml_keep_whitespaces_around_cdata = preserve
+ij_xml_keep_whitespaces_inside_cdata = false
+ij_xml_line_comment_at_first_column = true
+ij_xml_space_after_tag_name = false
+ij_xml_space_around_equals_in_attribute = false
+ij_xml_space_inside_empty_tag = false
+ij_xml_text_wrap = normal
+
+[{*.bash,*.sh,*.zsh}]
+ij_shell_binary_ops_start_line = false
+ij_shell_keep_column_alignment_padding = false
+ij_shell_minify_program = false
+ij_shell_redirect_followed_by_space = false
+ij_shell_switch_cases_indented = false
+ij_shell_use_unix_line_separator = true
+
+[{*.kt,*.kts}]
+ij_kotlin_align_in_columns_case_branch = false
+ij_kotlin_align_multiline_binary_operation = false
+ij_kotlin_align_multiline_extends_list = false
+ij_kotlin_align_multiline_method_parentheses = false
+ij_kotlin_align_multiline_parameters = true
+ij_kotlin_align_multiline_parameters_in_calls = false
+ij_kotlin_allow_trailing_comma = false
+ij_kotlin_allow_trailing_comma_on_call_site = false
+ij_kotlin_assignment_wrap = normal
+ij_kotlin_blank_lines_after_class_header = 0
+ij_kotlin_blank_lines_around_block_when_branches = 0
+ij_kotlin_blank_lines_before_declaration_with_comment_or_annotation_on_separate_line = 1
+ij_kotlin_block_comment_add_space = false
+ij_kotlin_block_comment_at_first_column = true
+ij_kotlin_call_parameters_new_line_after_left_paren = true
+ij_kotlin_call_parameters_right_paren_on_new_line = true
+ij_kotlin_call_parameters_wrap = on_every_item
+ij_kotlin_catch_on_new_line = false
+ij_kotlin_class_annotation_wrap = split_into_lines
+ij_kotlin_code_style_defaults = KOTLIN_OFFICIAL
+ij_kotlin_continuation_indent_for_chained_calls = false
+ij_kotlin_continuation_indent_for_expression_bodies = false
+ij_kotlin_continuation_indent_in_argument_lists = false
+ij_kotlin_continuation_indent_in_elvis = false
+ij_kotlin_continuation_indent_in_if_conditions = false
+ij_kotlin_continuation_indent_in_parameter_lists = false
+ij_kotlin_continuation_indent_in_supertype_lists = false
+ij_kotlin_else_on_new_line = false
+ij_kotlin_enum_constants_wrap = off
+ij_kotlin_extends_list_wrap = normal
+ij_kotlin_field_annotation_wrap = split_into_lines
+ij_kotlin_finally_on_new_line = false
+ij_kotlin_if_rparen_on_new_line = true
+ij_kotlin_import_nested_classes = false
+ij_kotlin_imports_layout = *,java.**,javax.**,kotlin.**,^
+ij_kotlin_indent_before_arrow_on_new_line = true
+ij_kotlin_insert_whitespaces_in_simple_one_line_method = true
+ij_kotlin_keep_blank_lines_before_right_brace = 2
+ij_kotlin_keep_blank_lines_in_code = 2
+ij_kotlin_keep_blank_lines_in_declarations = 2
+ij_kotlin_keep_first_column_comment = true
+ij_kotlin_keep_indents_on_empty_lines = false
+ij_kotlin_keep_line_breaks = true
+ij_kotlin_lbrace_on_next_line = false
+ij_kotlin_line_break_after_multiline_when_entry = true
+ij_kotlin_line_comment_add_space = false
+ij_kotlin_line_comment_add_space_on_reformat = false
+ij_kotlin_line_comment_at_first_column = true
+ij_kotlin_method_annotation_wrap = split_into_lines
+ij_kotlin_method_call_chain_wrap = normal
+ij_kotlin_method_parameters_new_line_after_left_paren = true
+ij_kotlin_method_parameters_right_paren_on_new_line = true
+ij_kotlin_method_parameters_wrap = on_every_item
+ij_kotlin_name_count_to_use_star_import = 5
+ij_kotlin_name_count_to_use_star_import_for_members = 3
+ij_kotlin_packages_to_use_import_on_demand = java.util.*,kotlinx.android.synthetic.**,io.ktor.**
+ij_kotlin_parameter_annotation_wrap = off
+ij_kotlin_space_after_comma = true
+ij_kotlin_space_after_extend_colon = true
+ij_kotlin_space_after_type_colon = true
+ij_kotlin_space_before_catch_parentheses = true
+ij_kotlin_space_before_comma = false
+ij_kotlin_space_before_extend_colon = true
+ij_kotlin_space_before_for_parentheses = true
+ij_kotlin_space_before_if_parentheses = true
+ij_kotlin_space_before_lambda_arrow = true
+ij_kotlin_space_before_type_colon = false
+ij_kotlin_space_before_when_parentheses = true
+ij_kotlin_space_before_while_parentheses = true
+ij_kotlin_spaces_around_additive_operators = true
+ij_kotlin_spaces_around_assignment_operators = true
+ij_kotlin_spaces_around_elvis = true
+ij_kotlin_spaces_around_equality_operators = true
+ij_kotlin_spaces_around_function_type_arrow = true
+ij_kotlin_spaces_around_logical_operators = true
+ij_kotlin_spaces_around_multiplicative_operators = true
+ij_kotlin_spaces_around_range = false
+ij_kotlin_spaces_around_relational_operators = true
+ij_kotlin_spaces_around_unary_operator = false
+ij_kotlin_spaces_around_when_arrow = true
+ij_kotlin_variable_annotation_wrap = off
+ij_kotlin_while_on_new_line = false
+ij_kotlin_wrap_elvis_expressions = 1
+ij_kotlin_wrap_expression_body_functions = 1
+ij_kotlin_wrap_first_method_in_call_chain = false
+
+[{*.har,*.json,*.jsonc,*.mcmeta,.prettierrc}]
+ij_json_array_wrapping = split_into_lines
+ij_json_keep_blank_lines_in_code = 0
+ij_json_keep_indents_on_empty_lines = false
+ij_json_keep_line_breaks = true
+ij_json_keep_trailing_comma = false
+ij_json_object_wrapping = split_into_lines
+ij_json_property_alignment = do_not_align
+ij_json_space_after_colon = true
+ij_json_space_after_comma = true
+ij_json_space_before_colon = false
+ij_json_space_before_comma = false
+ij_json_spaces_within_braces = false
+ij_json_spaces_within_brackets = false
+ij_json_wrap_long_lines = false
+
+[{*.htm,*.html,*.sht,*.shtm,*.shtml}]
+ij_html_add_new_line_before_tags = body,div,p,form,h1,h2,h3
+ij_html_align_attributes = true
+ij_html_align_text = false
+ij_html_attribute_wrap = normal
+ij_html_block_comment_add_space = false
+ij_html_block_comment_at_first_column = true
+ij_html_do_not_align_children_of_min_lines = 0
+ij_html_do_not_break_if_inline_tags = title,h1,h2,h3,h4,h5,h6,p
+ij_html_do_not_indent_children_of_tags = html,body,thead,tbody,tfoot
+ij_html_enforce_quotes = false
+ij_html_inline_tags = a,abbr,acronym,b,basefont,bdo,big,br,cite,cite,code,dfn,em,font,i,img,input,kbd,label,q,s,samp,select,small,span,strike,strong,sub,sup,textarea,tt,u,var
+ij_html_keep_blank_lines = 2
+ij_html_keep_indents_on_empty_lines = false
+ij_html_keep_line_breaks = true
+ij_html_keep_line_breaks_in_text = true
+ij_html_keep_whitespaces = false
+ij_html_keep_whitespaces_inside = span,pre,textarea
+ij_html_line_comment_at_first_column = true
+ij_html_new_line_after_last_attribute = never
+ij_html_new_line_before_first_attribute = never
+ij_html_quote_style = double
+ij_html_remove_new_line_before_tags = br
+ij_html_space_after_tag_name = false
+ij_html_space_around_equality_in_attribute = false
+ij_html_space_inside_empty_tag = false
+ij_html_text_wrap = normal
+
+[{*.markdown,*.md}]
+ij_markdown_force_one_space_after_blockquote_symbol = true
+ij_markdown_force_one_space_after_header_symbol = true
+ij_markdown_force_one_space_after_list_bullet = true
+ij_markdown_force_one_space_between_words = true
+ij_markdown_format_tables = true
+ij_markdown_insert_quote_arrows_on_wrap = true
+ij_markdown_keep_indents_on_empty_lines = false
+ij_markdown_keep_line_breaks_inside_text_blocks = true
+ij_markdown_max_lines_around_block_elements = 1
+ij_markdown_max_lines_around_header = 1
+ij_markdown_max_lines_between_paragraphs = 1
+ij_markdown_min_lines_around_block_elements = 1
+ij_markdown_min_lines_around_header = 1
+ij_markdown_min_lines_between_paragraphs = 1
+ij_markdown_wrap_text_if_long = true
+ij_markdown_wrap_text_inside_blockquotes = true
+
+[{*.toml,Cargo.lock,Cargo.toml.orig,Gopkg.lock,Pipfile,poetry.lock,uv.lock}]
+ij_toml_keep_indents_on_empty_lines = false
+
+[{*.yaml,*.yml}]
+ij_yaml_align_values_properties = do_not_align
+ij_yaml_autoinsert_sequence_marker = true
+ij_yaml_block_mapping_on_new_line = false
+ij_yaml_indent_sequence_value = true
+ij_yaml_keep_indents_on_empty_lines = false
+ij_yaml_keep_line_breaks = true
+ij_yaml_line_comment_add_space = false
+ij_yaml_line_comment_add_space_on_reformat = false
+ij_yaml_line_comment_at_first_column = true
+ij_yaml_sequence_on_new_line = false
+ij_yaml_space_before_colon = false
+ij_yaml_spaces_within_braces = true
+ij_yaml_spaces_within_brackets = true

.gitattributes

@@ -0,0 +1,11 @@
+# Use lf endings by default.
+* text=auto eol=lf
+
+# Declare text file types just in case
+*.java text
+*.yml text
+*.xml text
+*.md text
+
+# Exclude binary files
+*.png binary

.github/workflows/ci.yml

@@ -22,14 +22,21 @@ jobs:
           distribution: 'temurin'
           java-version: '21'
 
-      # TODO convert to a Gradle plugin later for portability
-      - name: Install Spigot dependency
-        run: ./scripts/install_spigot.sh 1.21.4
+      # We can't use 'maven' prebuilt cache setup because it requires that the project have a pom file.
+      # BuildTools installs to Maven local if available, so it's easier to just rely on that.
+      - name: Cache Spigot dependency
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.m2/repository/org/spigotmc/
+          key: ${{ runner.os }}-buildtools-${{ hashFiles('**/*.gradle*', '**/gradle-wrapper.properties') }}
+          restore-keys: |
+            ${{ runner.os }}-buildtools-
 
       - uses: gradle/actions/setup-gradle@v4
 
       - name: Build with Gradle
-        run: ./gradlew build
+        run: ./gradlew clean build
 
       # Upload artifacts
       - name: Upload Distributable Jar

.github/workflows/draft_release.yml

@@ -20,21 +20,15 @@ jobs:
 
       - name: Create Release
         id: create-release
-        uses: softprops/action-gh-release@v2.2.1
+        uses: softprops/action-gh-release@v2.3.2
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
-          name: ${{ env.VERSIONED_NAME }}
-          # May actually want to manually specify Paper versions all the time; they won't all
-          # need to be specified in code thanks to Mojang-mapped server internals.
-          # A bit annoying, but not terribly so.
-          # Instead, fetch min and max (which will also be Spigot version) and manually list intermediate versions?
+          name: OpenInv ${{ env.VERSIONED_NAME }}
           body: |-
             ## Supported server versions
-            ### Paper
-            TODO COMMA-SEPARATED VERSIONS
-            ### Spigot
-            TODO VERSION
+            **Paper:** TODO VERSION, 1.21.4, 1.21.3, 1.21.1
+            **Spigot:** TODO VERSION
             
             TODO HELLO HUMAN, PRESS THE GENERATE CHANGELOG BUTTON PLEASE.
           draft: true

README.md

@@ -1,7 +1,10 @@
 ## About
-OpenInv is a [Bukkit plugin](https://dev.bukkit.org/projects/openinv) which allows users to open and edit anyone's inventory or ender chest - online or not!
+
+OpenInv is a [Bukkit plugin](https://dev.bukkit.org/projects/openinv) which allows users to open and edit anyone's
+inventory or ender chest - online or not!
 
 ## Features
+
 - **OpenInv**: Open anyone's inventory, even if they're offline.
   - Read-only mode! Don't grant edit permission.
   - Cross-world support! Allow access only from the same world.
@@ -16,15 +19,19 @@ OpenInv is a [Bukkit plugin](https://dev.bukkit.org/projects/openinv) which allo
 - **AnyContainer**: Open containers, even if blocked by ocelots or blocks.
 
 ## Commands
+
 See [the wiki](https://github.com/Jikoo/OpenInv/wiki/Commands).
 
 ## Permissions
+
 See [the wiki](https://github.com/Jikoo/OpenInv/wiki/Permissions)
 
 ## For Developers
 
 ### As a Dependency
+
 The OpenInv API is available via [JitPack](https://jitpack.io/).
+
 ```xml
   <repositories>
     <repository>
@@ -33,6 +40,7 @@ The OpenInv API is available via [JitPack](https://jitpack.io/).
     </repository>
   </repositories>
 ```
+
 ```xml
   <dependencies>
     <dependency>
@@ -42,13 +50,13 @@ The OpenInv API is available via [JitPack](https://jitpack.io/).
     </dependency>
   </dependencies>
 ```
-Note that since JitPack only builds the API now, the "full" OpenInv jar on JitPack is actually the openinvapi artifact. This is a change from previous dependency declaration that I hope to revert.
+
+Note that since JitPack only builds the API now, the "full" OpenInv jar on JitPack is actually the openinvapi artifact.
+This is a change from previous dependency declaration that I hope to revert.
 
 ### Compilation
-To compile, the relevant Spigot jar must be installed in the local repository.
-As OpenInv is compiled against Mojang's mappings, you must run BuildTools with the `--remapped` argument:  
-`java -jar BuildTools.jar --remapped --rev $serverVersion`  
-`$serverVersion` is the version of the server, i.e. `1.21.4`
 
-Once Spigot is installed, execute the gradle wrapper:  
+Execute the gradle wrapper:  
 `./gradlew build`
+
+If you encounter issues with building the Spigot module, try running BuildTools manually.

addon/togglepersist/src/main/java/com/github/jikoo/openinv/togglepersist/TogglePersist.java

@@ -64,13 +64,16 @@ public class TogglePersist extends JavaPlugin implements Listener {
   }
 
   private void set(UUID playerId, String toggleName) {
-    enabledToggles.compute(playerId, (uuid, toggles) -> {
-      if (toggles == null) {
-        toggles = new HashSet<>();
-      }
-      toggles.add(toggleName);
-      return toggles;
-    });
+    enabledToggles.compute(
+        playerId,
+        (uuid, toggles) -> {
+          if (toggles == null) {
+            toggles = new HashSet<>();
+          }
+          toggles.add(toggleName);
+          return toggles;
+        }
+    );
   }
 
   @Override
@@ -97,13 +100,16 @@ public class TogglePersist extends JavaPlugin implements Listener {
       String idString = playerToggles.getKey().toString();
       for (String toggleName : playerToggles.getValue()) {
         // Add player ID to listing for each enabled toggle.
-        converted.compute(toggleName, (name, ids) -> {
-          if (ids == null) {
-            ids = new ArrayList<>();
-          }
-          ids.add(idString);
-          return ids;
-        });
+        converted.compute(
+            toggleName,
+            (name, ids) -> {
+              if (ids == null) {
+                ids = new ArrayList<>();
+              }
+              ids.add(idString);
+              return ids;
+            }
+        );
       }
     }
     return converted;
@@ -133,10 +139,13 @@ public class TogglePersist extends JavaPlugin implements Listener {
     if (event.isEnabled()) {
       set(event.getPlayerId(), event.getToggle().getName());
     } else {
-      enabledToggles.computeIfPresent(event.getPlayerId(), (uuid, toggles) -> {
-        toggles.remove(event.getToggle().getName());
-        return toggles.isEmpty() ? null : toggles;
-      });
+      enabledToggles.computeIfPresent(
+          event.getPlayerId(),
+          (uuid, toggles) -> {
+            toggles.remove(event.getToggle().getName());
+            return toggles.isEmpty() ? null : toggles;
+          }
+      );
     }
   }
 

api/build.gradle.kts

@@ -8,6 +8,7 @@ publishing {
     create<MavenPublication>("jitpack") {
       groupId = "com.github.Jikoo.OpenInv"
       artifactId = "openinvapi"
+      from(components["java"])
     }
   }
 }

api/src/main/java/com/lishid/openinv/IOpenInv.java

@@ -35,151 +35,157 @@ import java.util.logging.Logger;
  */
 public interface IOpenInv {
 
-    /**
-     * Check if the server version is supported by OpenInv.
-     *
-     * @return true if the server version is supported
-     */
-    boolean isSupportedVersion();
+  /**
+   * Check if the server version is supported by OpenInv.
+   *
+   * @return true if the server version is supported
+   */
+  boolean isSupportedVersion();
 
-    /**
-     * Check the configuration value for whether OpenInv saves player data when unloading players. This is exclusively
-     * for users who do not allow editing of inventories, only viewing, and wish to prevent any possibility of bugs such
-     * as lishid#40. If true, OpenInv will not ever save any edits made to players.
-     *
-     * @return false unless configured otherwise
-     */
-    boolean disableSaving();
+  /**
+   * Check the configuration value for whether OpenInv saves player data when unloading players. This is exclusively
+   * for users who do not allow editing of inventories, only viewing, and wish to prevent any possibility of bugs such
+   * as lishid#40. If true, OpenInv will not ever save any edits made to players.
+   *
+   * @return false unless configured otherwise
+   */
+  boolean disableSaving();
 
-    /**
-     * Check the configuration value for whether OpenInv allows offline access. If true, OpenInv will not load or allow
-     * modification of players while they are not online. This does not prevent other plugins from using existing loaded
-     * players who have gone offline.
-     *
-     * @return false unless configured otherwise
-     * @since 4.2.0
-     */
-    boolean disableOfflineAccess();
+  /**
+   * Check the configuration value for whether OpenInv allows offline access. If true, OpenInv will not load or allow
+   * modification of players while they are not online. This does not prevent other plugins from using existing loaded
+   * players who have gone offline.
+   *
+   * @return false unless configured otherwise
+   * @since 4.2.0
+   */
+  boolean disableOfflineAccess();
 
-    /**
-     * Check the configuration value for whether OpenInv uses history for opening commands. If false, OpenInv will use
-     * the previous parameterized search when no parameters are provided.
-     *
-     * @return false unless configured otherwise
-     * @since 4.3.0
-     */
-    boolean noArgsOpensSelf();
+  /**
+   * Check the configuration value for whether OpenInv uses history for opening commands. If false, OpenInv will use
+   * the previous parameterized search when no parameters are provided.
+   *
+   * @return false unless configured otherwise
+   * @since 4.3.0
+   */
+  boolean noArgsOpensSelf();
 
-    /**
-     * Get the active {@link IAnySilentContainer} implementation.
-     *
-     * @return the active implementation for the server version
-     * @throws IllegalStateException if the server version is unsupported
-     */
-    @NotNull IAnySilentContainer getAnySilentContainer();
+  /**
+   * Get the active {@link IAnySilentContainer} implementation.
+   *
+   * @return the active implementation for the server version
+   * @throws IllegalStateException if the server version is unsupported
+   */
+  @NotNull IAnySilentContainer getAnySilentContainer();
 
-    /**
-     * Get whether a user has AnyContainer mode enabled.
-     *
-     * @param offline the user to obtain the state of
-     * @return true if AnyContainer mode is enabled
-     */
-    boolean getAnyContainerStatus(@NotNull OfflinePlayer offline);
+  /**
+   * Get whether a user has AnyContainer mode enabled.
+   *
+   * @param offline the user to obtain the state of
+   * @return true if AnyContainer mode is enabled
+   */
+  boolean getAnyContainerStatus(@NotNull OfflinePlayer offline);
 
-    /**
-     * Set whether a user has AnyContainer mode enabled.
-     *
-     * @param offline the user to set the state of
-     * @param status the state of the mode
-     */
-    void setAnyContainerStatus(@NotNull OfflinePlayer offline, boolean status);
+  /**
+   * Set whether a user has AnyContainer mode enabled.
+   *
+   * @param offline the user to set the state of
+   * @param status the state of the mode
+   */
+  void setAnyContainerStatus(@NotNull OfflinePlayer offline, boolean status);
 
-    /**
-     * Get whether a user has SilentContainer mode enabled.
-     *
-     * @param offline the user to obtain the state of
-     * @return true if SilentContainer mode is enabled
-     */
-    boolean getSilentContainerStatus(@NotNull OfflinePlayer offline);
+  /**
+   * Get whether a user has SilentContainer mode enabled.
+   *
+   * @param offline the user to obtain the state of
+   * @return true if SilentContainer mode is enabled
+   */
+  boolean getSilentContainerStatus(@NotNull OfflinePlayer offline);
 
-    /**
-     * Set whether a user has SilentContainer mode enabled.
-     *
-     * @param offline the user to set the state of
-     * @param status the state of the mode
-     */
-    void setSilentContainerStatus(@NotNull OfflinePlayer offline, boolean status);
+  /**
+   * Set whether a user has SilentContainer mode enabled.
+   *
+   * @param offline the user to set the state of
+   * @param status the state of the mode
+   */
+  void setSilentContainerStatus(@NotNull OfflinePlayer offline, boolean status);
 
-    /**
-     * Get an {@link ISpecialEnderChest} for a user.
-     *
-     * @param player the {@link Player} owning the inventory
-     * @param online whether the owner is currently online
-     * @return the created inventory
-     * @throws IllegalStateException if the server version is unsupported
-     * @throws InstantiationException if there was an issue creating the inventory
-     */
-    @NotNull ISpecialEnderChest getSpecialEnderChest(@NotNull Player player, boolean online) throws InstantiationException;
+  /**
+   * Get an {@link ISpecialEnderChest} for a user.
+   *
+   * @param player the {@link Player} owning the inventory
+   * @param online whether the owner is currently online
+   * @return the created inventory
+   * @throws IllegalStateException if the server version is unsupported
+   * @throws InstantiationException if there was an issue creating the inventory
+   */
+  @NotNull ISpecialEnderChest getSpecialEnderChest(
+      @NotNull Player player,
+      boolean online
+  ) throws InstantiationException;
 
-    /**
-     * Get an {@link ISpecialPlayerInventory} for a user.
-     *
-     * @param player the {@link Player} owning the inventory
-     * @param online whether the owner is currently online
-     * @return the created inventory
-     * @throws IllegalStateException if the server version is unsupported
-     * @throws InstantiationException if there was an issue creating the inventory
-     */
-    @NotNull ISpecialPlayerInventory getSpecialInventory(@NotNull Player player, boolean online) throws InstantiationException;
+  /**
+   * Get an {@link ISpecialPlayerInventory} for a user.
+   *
+   * @param player the {@link Player} owning the inventory
+   * @param online whether the owner is currently online
+   * @return the created inventory
+   * @throws IllegalStateException if the server version is unsupported
+   * @throws InstantiationException if there was an issue creating the inventory
+   */
+  @NotNull ISpecialPlayerInventory getSpecialInventory(
+      @NotNull Player player,
+      boolean online
+  ) throws InstantiationException;
 
-    /**
-     * Open an {@link ISpecialInventory} for a {@link Player}.
-     *
-     * @param player the viewer
-     * @param inventory the inventory to open
-     * @return the resulting {@link InventoryView}
-     */
-    @Nullable InventoryView openInventory(@NotNull Player player, @NotNull ISpecialInventory inventory);
+  /**
+   * Open an {@link ISpecialInventory} for a {@link Player}.
+   *
+   * @param player the viewer
+   * @param inventory the inventory to open
+   * @return the resulting {@link InventoryView}
+   */
+  @Nullable InventoryView openInventory(@NotNull Player player, @NotNull ISpecialInventory inventory);
 
-    /**
-     * Check if a {@link Player} is currently loaded by OpenInv.
-     *
-     * @param playerUuid the {@link UUID} of the {@code Player}
-     * @return whether the {@code Player} is loaded
-     * @since 4.2.0
-     */
-    boolean isPlayerLoaded(@NotNull UUID playerUuid);
+  /**
+   * Check if a {@link Player} is currently loaded by OpenInv.
+   *
+   * @param playerUuid the {@link UUID} of the {@code Player}
+   * @return whether the {@code Player} is loaded
+   * @since 4.2.0
+   */
+  boolean isPlayerLoaded(@NotNull UUID playerUuid);
 
-    /**
-     * Load a {@link Player} from an {@link OfflinePlayer}. If the user has not played before or the default world for
-     * the server is not loaded, this will return {@code null}.
-     *
-     * @param offline the {@code OfflinePlayer} to load a {@code Player} for
-     * @return the loaded {@code Player}
-     * @throws IllegalStateException if the server version is unsupported
-     */
-    @Nullable Player loadPlayer(@NotNull final OfflinePlayer offline);
+  /**
+   * Load a {@link Player} from an {@link OfflinePlayer}. If the user has not played before or the default world for
+   * the server is not loaded, this will return {@code null}.
+   *
+   * @param offline the {@code OfflinePlayer} to load a {@code Player} for
+   * @return the loaded {@code Player}
+   * @throws IllegalStateException if the server version is unsupported
+   */
+  @Nullable Player loadPlayer(@NotNull final OfflinePlayer offline);
 
-    /**
-     * Match an existing {@link OfflinePlayer}. If the name is a {@link UUID#toString() UUID string}, this will only
-     * return the user if they have actually played on the server before, unlike {@link Bukkit#getOfflinePlayer(UUID)}.
-     *
-     * <p>This method is potentially very heavily blocking. It should not ever be called on the
-     * main thread, and if it is, a stack trace will be displayed alerting server owners to the
-     * call.
-     *
-     * @param name the string to match
-     * @return the user with the closest matching name
-     */
-    @Nullable OfflinePlayer matchPlayer(@NotNull String name);
+  /**
+   * Match an existing {@link OfflinePlayer}. If the name is a {@link UUID#toString() UUID string}, this will only
+   * return the user if they have actually played on the server before, unlike {@link Bukkit#getOfflinePlayer(UUID)}.
+   *
+   * <p>This method is potentially very heavily blocking. It should not ever be called on the
+   * main thread, and if it is, a stack trace will be displayed alerting server owners to the
+   * call.
+   *
+   * @param name the string to match
+   * @return the user with the closest matching name
+   */
+  @Nullable OfflinePlayer matchPlayer(@NotNull String name);
 
-    /**
-     * Forcibly close inventories of and unload any cached data for a user.
-     *
-     * @param offline the {@link OfflinePlayer} to unload
-     */
-    void unload(@NotNull OfflinePlayer offline);
+  /**
+   * Forcibly close inventories of and unload any cached data for a user.
+   *
+   * @param offline the {@link OfflinePlayer} to unload
+   */
+  void unload(@NotNull OfflinePlayer offline);
 
-    Logger getLogger();
+  Logger getLogger();
 
 }

api/src/main/java/com/lishid/openinv/event/OpenPlayerSaveEvent.java

@@ -26,8 +26,8 @@ public class OpenPlayerSaveEvent extends PlayerSaveEvent {
    */
   @RestrictedApi(
       explanation = "Constructor is not considered part of the API and may be subject to change.",
-      link = "",
-      allowedOnPath = ".*/com/lishid/openinv/event/OpenEvents.java")
+      allowedOnPath = ".*/com/lishid/openinv/event/OpenEvents.java"
+  )
   @ApiStatus.Internal
   OpenPlayerSaveEvent(@NotNull Player player, @NotNull ISpecialInventory inventory) {
     super(player);

api/src/main/java/com/lishid/openinv/event/PlayerSaveEvent.java

@@ -27,8 +27,8 @@ public class PlayerSaveEvent extends PlayerEvent implements Cancellable {
    */
   @RestrictedApi(
       explanation = "Constructor is not considered part of the API and may be subject to change.",
-      link = "",
-      allowedOnPath = ".*/com/lishid/openinv/event/(OpenPlayerSaveEvent|OpenEvents).java")
+      allowedOnPath = ".*/com/lishid/openinv/event/(OpenPlayerSaveEvent|OpenEvents).java"
+  )
   @ApiStatus.Internal
   PlayerSaveEvent(@NotNull Player player) {
     super(player);

api/src/main/java/com/lishid/openinv/event/PlayerToggledEvent.java

@@ -22,8 +22,8 @@ public class PlayerToggledEvent extends Event {
 
   @RestrictedApi(
       explanation = "Constructor is not considered part of the API and may be subject to change.",
-      link = "",
-      allowedOnPath = ".*/com/lishid/openinv/event/OpenEvents.java")
+      allowedOnPath = ".*/com/lishid/openinv/event/OpenEvents.java"
+  )
   @ApiStatus.Internal
   PlayerToggledEvent(@NotNull PlayerToggle toggle, @NotNull UUID uuid, boolean enabled) {
     this.toggle = toggle;

api/src/main/java/com/lishid/openinv/internal/IAnySilentContainer.java

@@ -29,94 +29,94 @@ import org.jetbrains.annotations.NotNull;
 
 public interface IAnySilentContainer {
 
-    /**
-     * Forcibly open the container at the given coordinates for the Player. This will open blocked containers! Be sure
-     * to check {@link #isAnyContainerNeeded(Block)} first if that is not desirable.
-     *
-     * @param player the {@link Player} opening the container
-     * @param silent whether the container's noise is to be silenced
-     * @param block  the {@link Block} of the container
-     * @return true if the container can be opened
-     */
-    boolean activateContainer(@NotNull Player player, boolean silent, @NotNull Block block);
+  /**
+   * Forcibly open the container at the given coordinates for the Player. This will open blocked containers! Be sure
+   * to check {@link #isAnyContainerNeeded(Block)} first if that is not desirable.
+   *
+   * @param player the {@link Player} opening the container
+   * @param silent whether the container's noise is to be silenced
+   * @param block  the {@link Block} of the container
+   * @return true if the container can be opened
+   */
+  boolean activateContainer(@NotNull Player player, boolean silent, @NotNull Block block);
 
-    /**
-     * Perform operations required to close the current container silently.
-     *
-     * @param player the {@link Player} closing a container
-     */
-    void deactivateContainer(@NotNull Player player);
+  /**
+   * Perform operations required to close the current container silently.
+   *
+   * @param player the {@link Player} closing a container
+   */
+  void deactivateContainer(@NotNull Player player);
 
-    /**
-     * Check if the container at the given coordinates is blocked.
-     *
-     * @param block the {@link Block} of the container
-     * @return true if the container is blocked
-     */
-    boolean isAnyContainerNeeded(@NotNull Block block);
+  /**
+   * Check if the container at the given coordinates is blocked.
+   *
+   * @param block the {@link Block} of the container
+   * @return true if the container is blocked
+   */
+  boolean isAnyContainerNeeded(@NotNull Block block);
 
-    /**
-     * Check if a shulker box block cannot be opened under ordinary circumstances.
-     *
-     * @param shulkerBox the shulker box block
-     * @return whether the container is blocked
-     */
-    default boolean isShulkerBlocked(@NotNull Block shulkerBox) {
-        Directional directional = (Directional) shulkerBox.getBlockData();
-        BlockFace facing = directional.getFacing();
-        // Construct a new 1-block bounding box at the origin.
-        BoundingBox box = new BoundingBox(0, 0, 0, 1, 1, 1);
-        // Expand the box in the direction the shulker will open.
-        box.expand(facing, 0.5);
-        // Move the box away from the origin by a block so only the expansion intersects with a box around the origin.
-        box.shift(facing.getOppositeFace().getDirection());
-        // Check if the relative block's collision shape (which will be at the origin) intersects with the expanded box.
-        return shulkerBox.getRelative(facing).getCollisionShape().overlaps(box);
-    }
+  /**
+   * Check if a shulker box block cannot be opened under ordinary circumstances.
+   *
+   * @param shulkerBox the shulker box block
+   * @return whether the container is blocked
+   */
+  default boolean isShulkerBlocked(@NotNull Block shulkerBox) {
+    Directional directional = (Directional) shulkerBox.getBlockData();
+    BlockFace facing = directional.getFacing();
+    // Construct a new 1-block bounding box at the origin.
+    BoundingBox box = new BoundingBox(0, 0, 0, 1, 1, 1);
+    // Expand the box in the direction the shulker will open.
+    box.expand(facing, 0.5);
+    // Move the box away from the origin by a block so only the expansion intersects with a box around the origin.
+    box.shift(facing.getOppositeFace().getDirection());
+    // Check if the relative block's collision shape (which will be at the origin) intersects with the expanded box.
+    return shulkerBox.getRelative(facing).getCollisionShape().overlaps(box);
+  }
 
-    /**
-     * Check if a chest cannot be opened under ordinary circumstances.
-     *
-     * @param chest the chest block
-     * @return whether the container is blocked
-     */
-    default boolean isChestBlocked(@NotNull Block chest) {
-        org.bukkit.block.Block relative = chest.getRelative(0, 1, 0);
-        return relative.getType().isOccluding()
-                || !chest.getWorld().getNearbyEntities(BoundingBox.of(relative), Cat.class::isInstance).isEmpty();
-    }
+  /**
+   * Check if a chest cannot be opened under ordinary circumstances.
+   *
+   * @param chest the chest block
+   * @return whether the container is blocked
+   */
+  default boolean isChestBlocked(@NotNull Block chest) {
+    org.bukkit.block.Block relative = chest.getRelative(0, 1, 0);
+    return relative.getType().isOccluding()
+        || !chest.getWorld().getNearbyEntities(BoundingBox.of(relative), Cat.class::isInstance).isEmpty();
+  }
 
-    /**
-     * Check if the given {@link Block} is a container which can be unblocked or silenced.
-     *
-     * @param block the potential container
-     * @return true if the type is a supported container
-     */
-    boolean isAnySilentContainer(@NotNull Block block);
+  /**
+   * Check if the given {@link Block} is a container which can be unblocked or silenced.
+   *
+   * @param block the potential container
+   * @return true if the type is a supported container
+   */
+  boolean isAnySilentContainer(@NotNull Block block);
 
-    /**
-     * Check if the given {@link BlockState} is a container which can be unblocked or silenced.
-     *
-     * @param blockState the potential container
-     * @return true if the type is a supported container
-     */
-    default boolean isAnySilentContainer(@NotNull BlockState blockState) {
-        return (blockState instanceof InventoryHolder holder && isAnySilentContainer(holder))
-                || blockState instanceof EnderChest;
-    }
+  /**
+   * Check if the given {@link BlockState} is a container which can be unblocked or silenced.
+   *
+   * @param blockState the potential container
+   * @return true if the type is a supported container
+   */
+  default boolean isAnySilentContainer(@NotNull BlockState blockState) {
+    return (blockState instanceof InventoryHolder holder && isAnySilentContainer(holder))
+        || blockState instanceof EnderChest;
+  }
 
-    /**
-     * Check if the given {@link InventoryHolder} is a container which can be unblocked or silenced.
-     *
-     * @param holder the potential container
-     * @return true if the type is a supported container
-     */
-    default boolean isAnySilentContainer(@NotNull InventoryHolder holder) {
-        return holder instanceof org.bukkit.block.EnderChest
-                || holder instanceof org.bukkit.block.Chest
-                || holder instanceof org.bukkit.block.DoubleChest
-                || holder instanceof org.bukkit.block.ShulkerBox
-                || holder instanceof org.bukkit.block.Barrel;
-    }
+  /**
+   * Check if the given {@link InventoryHolder} is a container which can be unblocked or silenced.
+   *
+   * @param holder the potential container
+   * @return true if the type is a supported container
+   */
+  default boolean isAnySilentContainer(@NotNull InventoryHolder holder) {
+    return holder instanceof org.bukkit.block.EnderChest
+        || holder instanceof org.bukkit.block.Chest
+        || holder instanceof org.bukkit.block.DoubleChest
+        || holder instanceof org.bukkit.block.ShulkerBox
+        || holder instanceof org.bukkit.block.Barrel;
+  }
 
 }

api/src/main/java/com/lishid/openinv/internal/ISpecialInventory.java

@@ -27,46 +27,49 @@ import org.jetbrains.annotations.NotNull;
  */
 public interface ISpecialInventory {
 
-    /**
-     * Get the {@link Inventory} associated with this {@code ISpecialInventory}.
-     *
-     * @return the Bukkit inventory
-     */
-    @NotNull Inventory getBukkitInventory();
+  /**
+   * Get the {@link Inventory} associated with this {@code ISpecialInventory}.
+   *
+   * @return the Bukkit inventory
+   */
+  @NotNull Inventory getBukkitInventory();
 
-    /**
-     * Get the {@link InventoryType} corresponding to this {@code ISpecialInventory}.
-     *
-     * @return the type of Bukkit inventory
-     */
-    @NotNull InventoryType getBukkitType();
+  /**
+   * Get the {@link InventoryType} corresponding to this {@code ISpecialInventory}.
+   *
+   * @return the type of Bukkit inventory
+   */
+  @NotNull InventoryType getBukkitType();
 
-    /**
-     * Set the owning {@link Player} instance to a newly-joined user.
-     *
-     * @param player the user coming online
-     */
-    void setPlayerOnline(@NotNull Player player);
+  /**
+   * Set the owning {@link Player} instance to a newly-joined user.
+   *
+   * @param player the user coming online
+   */
+  void setPlayerOnline(@NotNull Player player);
 
-    /**
-     * Mark the owner of the inventory offline.
-     */
-    void setPlayerOffline();
+  /**
+   * Mark the owner of the inventory offline.
+   *
+   * @deprecated No longer used by implementations.
+   */
+  @Deprecated(forRemoval = true, since = "5.1.11")
+  default void setPlayerOffline() {}
 
-    /**
-     * Get whether the inventory is being viewed by any users.
-     *
-     * @return true if the inventory is being viewed
-     */
-    default boolean isInUse() {
-        return !getBukkitInventory().getViewers().isEmpty();
-    }
+  /**
+   * Get whether the inventory is being viewed by any users.
+   *
+   * @return true if the inventory is being viewed
+   */
+  default boolean isInUse() {
+    return !getBukkitInventory().getViewers().isEmpty();
+  }
 
-    /**
-     * Get the {@link Player} who owns the inventory.
-     *
-     * @return the {@link HumanEntity} who owns the inventory
-     */
-    @NotNull HumanEntity getPlayer();
+  /**
+   * Get the {@link Player} who owns the inventory.
+   *
+   * @return the {@link HumanEntity} who owns the inventory
+   */
+  @NotNull HumanEntity getPlayer();
 
 }

api/src/main/java/com/lishid/openinv/internal/ISpecialPlayerInventory.java

@@ -24,9 +24,9 @@ import org.jetbrains.annotations.NotNull;
  */
 public interface ISpecialPlayerInventory extends ISpecialInventory {
 
-    @Override
-    default @NotNull InventoryType getBukkitType() {
-        return InventoryType.PLAYER;
-    }
+  @Override
+  default @NotNull InventoryType getBukkitType() {
+    return InventoryType.PLAYER;
+  }
 
 }

api/src/main/java/com/lishid/openinv/util/InventoryAccess.java

@@ -29,76 +29,78 @@ import java.util.function.BiFunction;
 
 public final class InventoryAccess {
 
-    private static @Nullable BiFunction<Inventory, Class<? extends ISpecialInventory>, ISpecialInventory> provider;
+  private static @Nullable BiFunction<Inventory, Class<? extends ISpecialInventory>, ISpecialInventory> provider;
 
-    public static boolean isUsable() {
-        return provider != null;
-    }
+  public static boolean isUsable() {
+    return provider != null;
+  }
 
-    /**
-     * Check if an {@link Inventory} is an {@link ISpecialPlayerInventory} implementation.
-     *
-     * @param inventory the Bukkit inventory
-     * @return true if backed by the correct implementation
-     */
-    public static boolean isPlayerInventory(@NotNull Inventory inventory) {
-        return getPlayerInventory(inventory) != null;
-    }
+  /**
+   * Check if an {@link Inventory} is an {@link ISpecialPlayerInventory} implementation.
+   *
+   * @param inventory the Bukkit inventory
+   * @return true if backed by the correct implementation
+   */
+  public static boolean isPlayerInventory(@NotNull Inventory inventory) {
+    return getPlayerInventory(inventory) != null;
+  }
 
-    /**
-     * Get the {@link ISpecialPlayerInventory} backing an {@link Inventory}. Returns {@code null} if the inventory is
-     * not backed by the correct class.
-     *
-     * @param inventory the Bukkit inventory
-     * @return the backing implementation if available
-     */
-    public static @Nullable ISpecialPlayerInventory getPlayerInventory(@NotNull Inventory inventory) {
-        return provider == null ? null : (ISpecialPlayerInventory) provider.apply(inventory, ISpecialPlayerInventory.class);
-    }
+  /**
+   * Get the {@link ISpecialPlayerInventory} backing an {@link Inventory}. Returns {@code null} if the inventory is
+   * not backed by the correct class.
+   *
+   * @param inventory the Bukkit inventory
+   * @return the backing implementation if available
+   */
+  public static @Nullable ISpecialPlayerInventory getPlayerInventory(@NotNull Inventory inventory) {
+    return provider == null ? null : (ISpecialPlayerInventory) provider.apply(inventory, ISpecialPlayerInventory.class);
+  }
 
-    /**
-     * Check if an {@link Inventory} is an {@link ISpecialEnderChest} implementation.
-     *
-     * @param inventory the Bukkit inventory
-     * @return true if backed by the correct implementation
-     */
-    public static boolean isEnderChest(@NotNull Inventory inventory) {
-        return getEnderChest(inventory) != null;
-    }
+  /**
+   * Check if an {@link Inventory} is an {@link ISpecialEnderChest} implementation.
+   *
+   * @param inventory the Bukkit inventory
+   * @return true if backed by the correct implementation
+   */
+  public static boolean isEnderChest(@NotNull Inventory inventory) {
+    return getEnderChest(inventory) != null;
+  }
 
-    /**
-     * Get the {@link ISpecialEnderChest} backing an {@link Inventory}. Returns {@code null} if the inventory is
-     * not backed by the correct class.
-     *
-     * @param inventory the Bukkit inventory
-     * @return the backing implementation if available
-     */
-    public static @Nullable ISpecialEnderChest getEnderChest(@NotNull Inventory inventory) {
-        return provider == null ? null : (ISpecialEnderChest) provider.apply(inventory, ISpecialEnderChest.class);
-    }
+  /**
+   * Get the {@link ISpecialEnderChest} backing an {@link Inventory}. Returns {@code null} if the inventory is
+   * not backed by the correct class.
+   *
+   * @param inventory the Bukkit inventory
+   * @return the backing implementation if available
+   */
+  public static @Nullable ISpecialEnderChest getEnderChest(@NotNull Inventory inventory) {
+    return provider == null ? null : (ISpecialEnderChest) provider.apply(inventory, ISpecialEnderChest.class);
+  }
 
-    /**
-     * Get a {@link ISpecialInventory} backing an {@link Inventory}. Returns {@code null} if the inventory is not backed
-     * by the correct class.
-     *
-     * @param inventory the Bukkit inventory
-     * @return the backing implementation if available
-     */
-    public static @Nullable ISpecialInventory getInventory(@NotNull Inventory inventory) {
-        return provider == null ? null : provider.apply(inventory, ISpecialInventory.class);
-    }
+  /**
+   * Get a {@link ISpecialInventory} backing an {@link Inventory}. Returns {@code null} if the inventory is not backed
+   * by the correct class.
+   *
+   * @param inventory the Bukkit inventory
+   * @return the backing implementation if available
+   */
+  public static @Nullable ISpecialInventory getInventory(@NotNull Inventory inventory) {
+    return provider == null ? null : provider.apply(inventory, ISpecialInventory.class);
+  }
 
-    @RestrictedApi(
-        explanation = "Not part of the API.",
-        link = "",
-        allowedOnPath = ".*/com/lishid/openinv/util/InternalAccessor.java")
-    @ApiStatus.Internal
-    static void setProvider(@Nullable BiFunction<Inventory, Class<? extends ISpecialInventory>, ISpecialInventory> provider) {
-        InventoryAccess.provider = provider;
-    }
+  @RestrictedApi(
+      explanation = "Not part of the API.",
+      allowedOnPath = ".*/com/lishid/openinv/util/InternalAccessor.java"
+  )
+  @ApiStatus.Internal
+  static void setProvider(
+      @Nullable BiFunction<Inventory, Class<? extends ISpecialInventory>, ISpecialInventory> provider
+  ) {
+    InventoryAccess.provider = provider;
+  }
 
-    private InventoryAccess() {
-        throw new IllegalStateException("Cannot create instance of utility class.");
-    }
+  private InventoryAccess() {
+    throw new IllegalStateException("Cannot create instance of utility class.");
+  }
 
 }

build.gradle.kts

@@ -2,6 +2,7 @@ plugins {
   `java-library`
   alias(libs.plugins.paperweight) apply false
   alias(libs.plugins.shadow) apply false
+  id(libs.plugins.errorprone.gradle.get().pluginId) apply false
 }
 
 // Set by Spigot module, used by Paper module to convert to Spigot's version of Mojang mappings.

buildSrc/build.gradle.kts

@@ -4,4 +4,11 @@ plugins {
 
 repositories {
   gradlePluginPortal()
+  mavenCentral()
+}
+
+dependencies {
+  val libs = project.extensions.getByType(VersionCatalogsExtension::class.java).named("libs")
+  implementation(libs.findLibrary("specialsource").orElseThrow())
+  implementation(libs.findLibrary("errorprone-gradle").orElseThrow())
 }

buildSrc/settings.gradle.kts

@@ -0,0 +1,7 @@
+dependencyResolutionManagement {
+  versionCatalogs {
+    create("libs") {
+      from(files("../gradle/libs.versions.toml"))
+    }
+  }
+}

buildSrc/src/main/kotlin/com/github/jikoo/openinv/BuildToolsValueSource.kt

@@ -0,0 +1,100 @@
+package com.github.jikoo.openinv
+
+import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.provider.Property
+import org.gradle.api.provider.ValueSource
+import org.gradle.api.provider.ValueSourceParameters
+import org.gradle.process.ExecOperations
+import java.io.File
+import java.net.URI
+import java.nio.file.Files
+import javax.inject.Inject
+
+abstract class BuildToolsValueSource : ValueSource<File, BuildToolsValueSource.Parameters> {
+
+  @get:Inject
+  abstract val exec: ExecOperations
+
+  interface Parameters : ValueSourceParameters {
+    val mavenLocal: Property<File>
+    val workingDir: DirectoryProperty
+
+    val spigotVersion: Property<String>
+    val spigotRevision: Property<String>
+
+    val ignoreCached: Property<Boolean>
+
+    val javaHome: DirectoryProperty
+    val javaExecutable: Property<String>
+  }
+
+  override fun obtain(): File {
+    val version = parameters.spigotVersion.get()
+    val revision = parameters.spigotRevision.get()
+    val installLocation = getInstallLocation(version)
+    // If Spigot is already installed, don't reinstall.
+    if (!parameters.ignoreCached.get() && installLocation.exists()) {
+      println("Skipping Spigot installation, $version is present")
+      return installLocation
+    }
+
+    val buildTools = installBuildTools(parameters.workingDir.get().asFile)
+
+    println("Installing Spigot $version (rev $revision)")
+
+    exec.javaexec {
+      environment["JAVA_HOME"] = parameters.javaHome.get()
+      executable = parameters.javaExecutable.get()
+      workingDir = buildTools.parentFile
+      classpath(buildTools)
+      args = listOf("--nogui", "--rev", revision, "--remapped")
+    }.rethrowFailure()
+
+    // Mark work for delete.
+    cleanUp(buildTools.parentFile)
+
+    if (!installLocation.exists()) {
+      throw IllegalStateException(
+        "Failed to install Spigot $version from $revision. Does the revision point to a different version?"
+      )
+    }
+    return installLocation
+  }
+
+  private fun getInstallLocation(version: String): File {
+    return parameters.mavenLocal.get().resolve("org/spigotmc/spigot/$version/spigot-$version-remapped-mojang.jar")
+  }
+
+  private fun installBuildTools(workingDir: File): File {
+    val buildTools = workingDir.resolve("BuildTools.jar")
+    if (buildTools.exists()) {
+      return buildTools
+    }
+
+    workingDir.mkdirs()
+
+    val buildToolsUrl =
+      "https://hub.spigotmc.org/jenkins/job/BuildTools/lastSuccessfulBuild/artifact/target/BuildTools.jar"
+    println("Downloading $buildToolsUrl")
+    val stream = URI.create(buildToolsUrl).toURL().openStream()
+    Files.copy(stream, buildTools.toPath())
+    stream.close()
+
+    return buildTools
+  }
+
+  private fun cleanUp(dir: File) {
+    dir.deleteOnExit()
+    if (!dir.isDirectory) {
+      return
+    }
+
+    dir.listFiles()?.forEach {
+      if (it.isDirectory) {
+        cleanUp(it)
+      } else {
+        it.deleteOnExit()
+      }
+    }
+  }
+}

buildSrc/src/main/kotlin/com/github/jikoo/openinv/SpigotDependencyExtension.kt

@@ -0,0 +1,21 @@
+package com.github.jikoo.openinv
+
+import org.gradle.api.model.ObjectFactory
+import org.gradle.jvm.toolchain.JavaToolchainSpec
+
+abstract class SpigotDependencyExtension(
+  objects: ObjectFactory
+) {
+
+  val version = objects.property(String::class.java)
+  val revision = objects.property(String::class.java)
+    .convention(version.map {
+      it.replace("-R\\d+\\.\\d+-SNAPSHOT".toRegex(), "")
+    })
+  val configuration = objects.property(String::class.java)
+  val classifier = objects.property(String::class.java).convention("remapped-mojang")
+  val ext = objects.property(String::class.java)
+  val java = objects.property(JavaToolchainSpec::class.java)
+  val ignoreCached = objects.property(Boolean::class.java).convention(false)
+
+}

buildSrc/src/main/kotlin/com/github/jikoo/openinv/SpigotReobf.kt

@@ -0,0 +1,56 @@
+package com.github.jikoo.openinv
+
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+import org.gradle.api.attributes.Bundling
+import org.gradle.api.attributes.Category
+import org.gradle.api.attributes.LibraryElements
+import org.gradle.api.attributes.Usage
+import org.gradle.jvm.tasks.Jar
+import org.gradle.kotlin.dsl.named
+import org.gradle.kotlin.dsl.register
+import java.nio.file.Paths
+
+class SpigotReobf : Plugin<Project> {
+
+  companion object {
+    const val ARTIFACT_CONFIG = "reobf"
+  }
+
+  override fun apply(target: Project) {
+    // Re-use extension from Spigot dependency declaration if available to reduce configuration requirements.
+    val spigotExt = target.dependencies.extensions.findByType(SpigotDependencyExtension::class.java)
+      ?: target.dependencies.extensions.create(
+        "spigot",
+        SpigotDependencyExtension::class.java,
+        target.objects
+      )
+
+    val mvnLocal = target.repositories.mavenLocal()
+
+    val reobfTask = target.tasks.register<SpigotReobfTask>("reobfTask") {
+      dependsOn(target.tasks.named("shadowJar"))
+      // ShadowJar extends Jar, so this should be a safe way to get the result without having
+      // to jump through hoops and shift around shadow declarations in the rest of the project.
+      inputFile.convention(target.tasks.named<Jar>("shadowJar").get().archiveFile)
+      spigotVersion.convention(spigotExt.version)
+      getMavenLocal().set(Paths.get(mvnLocal.url).toFile())
+    }
+
+    // Set up configuration for producing reobf jar.
+    target.configurations.consumable(ARTIFACT_CONFIG) {
+      attributes {
+        attribute(Category.CATEGORY_ATTRIBUTE, target.objects.named(Category.LIBRARY))
+        attribute(Usage.USAGE_ATTRIBUTE, target.objects.named(Usage.JAVA_RUNTIME))
+        attribute(Bundling.BUNDLING_ATTRIBUTE, target.objects.named(Bundling.EXTERNAL))
+        attribute(LibraryElements.LIBRARY_ELEMENTS_ATTRIBUTE, target.objects.named(LibraryElements.JAR))
+      }
+    }
+
+    // Add artifact from reobf task.
+    target.artifacts {
+      add(ARTIFACT_CONFIG, reobfTask)
+    }
+  }
+
+}

buildSrc/src/main/kotlin/com/github/jikoo/openinv/SpigotReobfTask.kt

@@ -0,0 +1,85 @@
+package com.github.jikoo.openinv
+
+import net.md_5.specialsource.Jar
+import net.md_5.specialsource.JarMapping
+import net.md_5.specialsource.JarRemapper
+import net.md_5.specialsource.RemapperProcessor
+import net.md_5.specialsource.provider.JarProvider
+import net.md_5.specialsource.provider.JointProvider
+import org.gradle.api.file.RegularFileProperty
+import org.gradle.api.provider.Property
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.InputFile
+import org.gradle.api.tasks.Internal
+import org.gradle.api.tasks.TaskAction
+import java.io.File
+
+abstract class SpigotReobfTask : org.gradle.api.tasks.bundling.Jar() {
+
+  @get:Input
+  val spigotVersion: Property<String> = objectFactory.property(String::class.java)
+
+  @get:InputFile
+  val inputFile: RegularFileProperty = objectFactory.fileProperty()
+
+  @get:Input
+  val intermediaryClassifier: Property<String> = objectFactory.property(String::class.java).convention("mojang-mapped")
+
+  private val mavenLocal: Property<File> = objectFactory.property(File::class.java)
+
+  init {
+    archiveClassifier.convention(SpigotReobf.ARTIFACT_CONFIG)
+  }
+
+  @TaskAction
+  override fun copy() {
+    val spigotVer = spigotVersion.get()
+    val inFile = inputFile.get().asFile
+    val obfPath = inFile.resolveSibling(inFile.name.replace(".jar", "-${intermediaryClassifier.get()}.jar"))
+
+    // https://www.spigotmc.org/threads/510208/#post-4184317
+    val repo = mavenLocal.get()
+    val spigotDir = repo.resolve("org/spigotmc/spigot/$spigotVer/")
+    val mappingDir = repo.resolve("org/spigotmc/minecraft-server/$spigotVer/")
+
+    // Remap original Mojang-mapped jar to obfuscated intermediary
+    val mojangServer = spigotDir.resolve("spigot-$spigotVer-remapped-mojang.jar")
+    val mojangMappings = mappingDir.resolve("minecraft-server-$spigotVer-maps-mojang.txt")
+    remapPartial(mojangServer, mojangMappings, inFile, obfPath, true)
+
+    // Remap obfuscated intermediary jar to Spigot and replace original
+    val obfServer = spigotDir.resolve("spigot-$spigotVer-remapped-obf.jar")
+    val spigotMappings = mappingDir.resolve("minecraft-server-$spigotVer-maps-spigot.csrg")
+    remapPartial(obfServer, spigotMappings, obfPath, archiveFile.get().asFile, false)
+  }
+
+  private fun remapPartial(server: File, mapping: File, input: File, output: File, reverse: Boolean) {
+    val jarMapping = JarMapping()
+    jarMapping.loadMappings(mapping.path, reverse, false, null, null)
+
+    val inheritance = JointProvider()
+    jarMapping.setFallbackInheritanceProvider(inheritance)
+
+    // Equivalent of --live with server jar on classpath.
+    val serverJar = Jar.init(server)
+    inheritance.add(JarProvider(serverJar))
+
+    val inputJar = Jar.init(input)
+    inheritance.add(JarProvider(inputJar))
+
+    // Remap reflective access.
+    val preprocessor = RemapperProcessor(null, jarMapping, null)
+
+    val remapper = JarRemapper(preprocessor, jarMapping, null)
+    remapper.remapJar(inputJar, output, emptySet())
+
+    serverJar.close()
+    inputJar.close()
+  }
+
+  @Internal
+  internal fun getMavenLocal(): Property<File> {
+    return mavenLocal
+  }
+
+}

buildSrc/src/main/kotlin/com/github/jikoo/openinv/SpigotSetup.kt

@@ -0,0 +1,60 @@
+package com.github.jikoo.openinv
+
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+import org.gradle.api.plugins.JavaPluginExtension
+import org.gradle.jvm.toolchain.JavaToolchainService
+import org.gradle.kotlin.dsl.create
+import java.nio.file.Paths
+import javax.inject.Inject
+
+abstract class SpigotSetup : Plugin<Project> {
+
+  @get:Inject
+  abstract val javaToolchainService: JavaToolchainService
+
+  override fun apply(target: Project) {
+    target.plugins.apply("java")
+
+    // Set up extension for configuring Spigot dependency.
+    val spigotExt = target.dependencies.extensions.findByType(SpigotDependencyExtension::class.java)
+      ?: target.dependencies.extensions.create(
+        "spigot",
+        SpigotDependencyExtension::class.java,
+        target.objects
+      )
+
+    val mvnLocal = target.repositories.mavenLocal()
+
+    target.afterEvaluate {
+      // Get Java requirements, defaulting to version used for compilation.
+      spigotExt.java.convention(target.extensions.getByType(JavaPluginExtension::class.java).toolchain)
+      val launcher = javaToolchainService.launcherFor(spigotExt.java.get()).get()
+
+      // Install Spigot with BuildTools.
+      target.providers.of(BuildToolsValueSource::class.java) {
+        parameters {
+          mavenLocal.set(Paths.get(mvnLocal.url).toFile())
+          workingDir.set(target.layout.buildDirectory.dir("tmp/buildtools"))
+          spigotVersion.set(spigotExt.version)
+          spigotRevision.set(spigotExt.revision)
+          ignoreCached.set(spigotExt.ignoreCached)
+          javaHome.set(launcher.metadata.installationPath)
+          javaExecutable.set(launcher.executablePath.asFile.path)
+        }
+      }.get()
+
+      // Add Spigot dependency.
+      val dependency = target.dependencies.create(
+        "org.spigotmc",
+        "spigot",
+        spigotExt.version.get(),
+        spigotExt.configuration.orNull,
+        spigotExt.classifier.orNull,
+        spigotExt.ext.orNull
+      )
+      target.dependencies.add("compileOnly", dependency)
+    }
+  }
+
+}

buildSrc/src/main/kotlin/openinv-base.gradle.kts

@@ -1,10 +1,6 @@
-import org.gradle.jvm.toolchain.JavaLanguageVersion
-import org.gradle.kotlin.dsl.maven
-import org.gradle.kotlin.dsl.repositories
-import org.gradle.kotlin.dsl.dependencies
-
 plugins {
   `java-library`
+  id("net.ltgt.errorprone")
 }
 
 java {
@@ -21,6 +17,7 @@ dependencies {
   val libs = versionCatalogs.named("libs")
   compileOnly(libs.findLibrary("annotations").orElseThrow())
   compileOnly(libs.findLibrary("spigotapi").orElseThrow())
+  errorprone(libs.findLibrary("errorprone-core").orElseThrow())
 }
 
 tasks {

buildSrc/src/main/kotlin/remap-spigot.gradle.kts

@@ -1,55 +0,0 @@
-import java.nio.file.Path
-import java.nio.file.Paths
-
-val spigotRemap = configurations.create("spigotRemap")
-
-repositories {
-  mavenCentral()
-}
-
-dependencies {
-  spigotRemap("net.md-5:SpecialSource:1.11.4:shaded")
-}
-
-abstract class RemapTask
-  @Inject constructor(private val project: Project): DefaultTask() {
-
-  @get:Input
-  abstract var spigotVersion: String
-
-  @TaskAction
-  fun remapInputs() {
-    inputs.files.forEach {
-      remap(spigotVersion, it.toPath(), it.toPath().resolveSibling(it.name.replace(".jar", "-obf.jar")))
-    }
-  }
-
-  private fun remap(spigotVersion: String, jarPath: Path, obfPath: Path) {
-    // https://www.spigotmc.org/threads/510208/#post-4184317
-    val specialsource = project.configurations.named("spigotRemap").get().incoming.artifacts.artifacts
-      .first { it.id.componentIdentifier.toString() == "net.md-5:SpecialSource:1.11.4" }.file.path
-    val repo = Paths.get(project.repositories.mavenLocal().url)
-    val spigotDir = repo.resolve("org/spigotmc/spigot/$spigotVersion/")
-    val mappingDir = repo.resolve("org/spigotmc/minecraft-server/$spigotVersion/")
-
-    // Remap original Mojang-mapped jar to obfuscated intermediary
-    val mojangServer = spigotDir.resolve("spigot-$spigotVersion-remapped-mojang.jar")
-    val mojangMappings = mappingDir.resolve("minecraft-server-$spigotVersion-maps-mojang.txt")
-    remapPartial(specialsource, mojangServer, mojangMappings, jarPath, obfPath, true)
-
-    // Remap obfuscated intermediary jar to Spigot and replace original
-    val obfServer = spigotDir.resolve("spigot-$spigotVersion-remapped-obf.jar")
-    val spigotMappings = mappingDir.resolve("minecraft-server-$spigotVersion-maps-spigot.csrg")
-    remapPartial(specialsource, obfServer, spigotMappings, obfPath, jarPath, false)
-  }
-
-  private fun remapPartial(specialSource: String, serverJar: Path, mapping: Path, input: Path, output: Path, reverse: Boolean) {
-    project.providers.exec {
-      commandLine("java", "-cp", "$specialSource${File.pathSeparator}$serverJar",
-        "net.md_5.specialsource.SpecialSource", "--live",
-        "-i", "$input", "-o", "$output",
-        "-m", "$mapping",
-        if (reverse) "--reverse" else "")
-    }.result.get()
-  }
-}

common/build.gradle.kts

@@ -4,4 +4,5 @@ plugins {
 
 dependencies {
   implementation(project(":openinvapi"))
+  compileOnly(libs.slf4j.api)
 }

common/src/main/java/com/lishid/openinv/internal/InventoryViewTitle.java

@@ -1,48 +0,0 @@
-package com.lishid.openinv.internal;
-
-import com.lishid.openinv.util.lang.LanguageManager;
-import com.lishid.openinv.util.lang.Replacement;
-import org.bukkit.entity.HumanEntity;
-import org.bukkit.entity.Player;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-import java.util.Objects;
-
-public enum InventoryViewTitle {
-
-  PLAYER_INVENTORY("container.player", "'s Inventory"),
-  ENDER_CHEST("container.enderchest", "'s Ender Chest");
-
-  private final String localizationKey;
-  private final String defaultSuffix;
-
-  InventoryViewTitle(String localizationKey, String defaultSuffix) {
-    this.localizationKey = localizationKey;
-    this.defaultSuffix = defaultSuffix;
-  }
-
-  public @NotNull String getTitle(
-      @NotNull LanguageManager lang,
-      @NotNull Player viewer,
-      @NotNull ISpecialInventory inventory) {
-    HumanEntity owner = inventory.getPlayer();
-
-    String localTitle = lang.getLocalizedMessage(
-            viewer,
-            localizationKey,
-            new Replacement("%player%", owner.getName()));
-    return Objects.requireNonNullElseGet(localTitle, () -> owner.getName() + defaultSuffix);
-  }
-
-  public static @Nullable InventoryViewTitle of(@NotNull ISpecialInventory inventory) {
-    if (inventory instanceof ISpecialPlayerInventory) {
-      return PLAYER_INVENTORY;
-    } else if (inventory instanceof ISpecialEnderChest) {
-      return ENDER_CHEST;
-    } else {
-      return null;
-    }
-  }
-
-}

common/src/main/java/com/lishid/openinv/internal/PlayerManager.java

@@ -24,31 +24,31 @@ import org.jetbrains.annotations.Nullable;
 
 public interface PlayerManager {
 
-    /**
-     * Loads a Player for an OfflinePlayer.
-     * </p>
-     * This method is potentially blocking, and should not be called on the main thread.
-     *
-     * @param offline the OfflinePlayer
-     * @return the Player loaded
-     */
-    @Nullable Player loadPlayer(@NotNull OfflinePlayer offline);
+  /**
+   * Loads a Player for an OfflinePlayer.
+   * </p>
+   * This method is potentially blocking, and should not be called on the main thread.
+   *
+   * @param offline the OfflinePlayer
+   * @return the Player loaded
+   */
+  @Nullable Player loadPlayer(@NotNull OfflinePlayer offline);
 
-    /**
-     * Creates a new Player from an existing one that will function slightly better offline.
-     *
-     * @return the Player
-     */
-    @NotNull Player inject(@NotNull Player player);
+  /**
+   * Creates a new Player from an existing one that will function slightly better offline.
+   *
+   * @return the Player
+   */
+  @NotNull Player inject(@NotNull Player player);
 
-    /**
-     * Opens an ISpecialInventory for a Player.
-     *
-     * @param player the Player opening the ISpecialInventory
-     * @param inventory the Inventory
-     *`
-     * @return the InventoryView opened
-     */
-    @Nullable InventoryView openInventory(@NotNull Player player, @NotNull ISpecialInventory inventory, boolean viewOnly);
+  /**
+   * Opens an ISpecialInventory for a Player.
+   *
+   * @param player the Player opening the ISpecialInventory
+   * @param inventory the Inventory
+   *
+   * @return the InventoryView opened
+   */
+  @Nullable InventoryView openInventory(@NotNull Player player, @NotNull ISpecialInventory inventory, boolean viewOnly);
 
 }

common/src/main/java/com/lishid/openinv/util/JulLoggerAdapter.java

@@ -0,0 +1,134 @@
+package com.lishid.openinv.util;
+
+import org.slf4j.Marker;
+import org.slf4j.helpers.LegacyAbstractLogger;
+import org.slf4j.helpers.MessageFormatter;
+import org.slf4j.helpers.NormalizedParameters;
+import org.slf4j.spi.LocationAwareLogger;
+
+import java.util.logging.Level;
+import java.util.logging.LogRecord;
+import java.util.logging.Logger;
+
+/**
+ * An adapter for wrapping a {@link java.util.logging.Logger} as a {@link org.slf4j.Logger}.
+ * <br>Largely based on {@code JDK14LoggerAdapter}, which is not present at runtime.
+ */
+public class JulLoggerAdapter extends LegacyAbstractLogger implements LocationAwareLogger {
+
+  private final Logger wrapped;
+
+  public JulLoggerAdapter(Logger wrapped) {
+    this.wrapped = wrapped;
+    this.name = wrapped.getName();
+  }
+
+  @Override
+  protected String getFullyQualifiedCallerName() {
+    return JulLoggerAdapter.class.getName();
+  }
+
+  @Override
+  protected void handleNormalizedLoggingCall(
+      org.slf4j.event.Level slf4jLevel,
+      Marker marker,
+      String msg,
+      Object[] args,
+      Throwable thrown
+  ) {
+    Level level = fromSlf4jLevel(slf4jLevel);
+
+    if (wrapped.isLoggable(level)) {
+      normalizedLog(getFullyQualifiedCallerName(), level, msg, args, thrown);
+    }
+  }
+
+  private void normalizedLog(String fqcn, Level level, String msg, Object[] args, Throwable thrown) {
+    String formatted = MessageFormatter.basicArrayFormat(msg, args);
+    LogRecord logRecord = new LogRecord(level, formatted);
+    logRecord.setLoggerName(getName());
+    logRecord.setThrown(thrown);
+
+    addSource(fqcn, logRecord);
+
+    wrapped.log(logRecord);
+  }
+
+  private void addSource(String fqcn, LogRecord logRecord) {
+    // TODO stackwalker?
+    StackTraceElement[] trace = new Throwable().getStackTrace();
+    int maxElements = 12;
+    int lastIgnored = maxElements;
+    // Start from 2; 0 is above and 1 is caller of internal method.
+    for (int i = 2; i < maxElements; ++i) {
+      if (isIgnored(trace[i].getClassName(), fqcn)) {
+        lastIgnored = i;
+      }
+    }
+
+    if (lastIgnored < maxElements - 1) {
+      StackTraceElement caller = trace[lastIgnored + 1];
+      logRecord.setSourceClassName(caller.getClassName());
+      logRecord.setSourceMethodName(caller.getMethodName());
+    }
+  }
+
+  private boolean isIgnored(String className, String fqcn) {
+    if (className.equals(fqcn)) {
+      return true;
+    }
+    // Ignore slf4j classes - they shouldn't be the source.
+    if (className.startsWith("org.slf4j.")) {
+      return true;
+    }
+    return className.equals(getFullyQualifiedCallerName());
+  }
+
+  @Override
+  public void log(Marker marker, String callerFqn, int levelInt, String msg, Object[] args, Throwable thrown) {
+    Level level = fromSlf4jLevel(org.slf4j.event.Level.intToLevel(levelInt));
+
+    if (!wrapped.isLoggable(level)) {
+      return;
+    }
+
+    NormalizedParameters params = NormalizedParameters.normalize(msg, args, thrown);
+    normalizedLog(callerFqn, level, params.getMessage(), params.getArguments(), params.getThrowable());
+  }
+
+  private Level fromSlf4jLevel(org.slf4j.event.Level level) {
+    return switch (level) {
+      case TRACE -> Level.FINEST;
+      case DEBUG -> Level.FINE;
+      case INFO -> Level.INFO;
+      case WARN -> Level.WARNING;
+      case ERROR -> Level.SEVERE;
+    };
+  }
+
+  @Override
+  public boolean isTraceEnabled() {
+    return wrapped.isLoggable(Level.FINEST);
+  }
+
+  @Override
+  public boolean isDebugEnabled() {
+    return wrapped.isLoggable(Level.FINE);
+  }
+
+  @Override
+  public boolean isInfoEnabled() {
+    return wrapped.isLoggable(Level.INFO);
+  }
+
+  @Override
+  public boolean isWarnEnabled() {
+    return wrapped.isLoggable(Level.WARNING);
+  }
+
+  @Override
+  public boolean isErrorEnabled() {
+    return wrapped.isLoggable(Level.SEVERE);
+  }
+
+}

common/src/main/java/com/lishid/openinv/util/Permissions.java

@@ -21,40 +21,43 @@ import org.jetbrains.annotations.NotNull;
 
 public enum Permissions {
 
-    INVENTORY_OPEN_SELF("inventory.open.self"),
-    INVENTORY_OPEN_OTHER("inventory.open.other"),
-    INVENTORY_EDIT_SELF("inventory.edit.self"),
-    INVENTORY_EDIT_OTHER("inventory.edit.other"),
-    INVENTORY_SLOT_HEAD_ANY("inventory.slot.head.any"),
-    INVENTORY_SLOT_CHEST_ANY("inventory.slot.chest.any"),
-    INVENTORY_SLOT_LEGS_ANY("inventory.slot.legs.any"),
-    INVENTORY_SLOT_FEET_ANY("inventory.slot.feet.any"),
-    INVENTORY_SLOT_DROP("inventory.slot.drop"),
+  INVENTORY_OPEN_SELF("inventory.open.self"),
+  INVENTORY_OPEN_OTHER("inventory.open.other"),
+  INVENTORY_EDIT_SELF("inventory.edit.self"),
+  INVENTORY_EDIT_OTHER("inventory.edit.other"),
+  INVENTORY_SLOT_HEAD_ANY("inventory.slot.head.any"),
+  INVENTORY_SLOT_CHEST_ANY("inventory.slot.chest.any"),
+  INVENTORY_SLOT_LEGS_ANY("inventory.slot.legs.any"),
+  INVENTORY_SLOT_FEET_ANY("inventory.slot.feet.any"),
+  INVENTORY_SLOT_DROP("inventory.slot.drop"),
 
-    ENDERCHEST_OPEN_SELF("enderchest.open.self"),
-    ENDERCHEST_OPEN_OTHER("enderchest.open.other"),
-    ENDERCHEST_EDIT_SELF("enderchest.edit.self"),
-    ENDERCHEST_EDIT_OTHER("enderchest.edit.other"),
+  ENDERCHEST_OPEN_SELF("enderchest.open.self"),
+  ENDERCHEST_OPEN_OTHER("enderchest.open.other"),
+  ENDERCHEST_EDIT_SELF("enderchest.edit.self"),
+  ENDERCHEST_EDIT_OTHER("enderchest.edit.other"),
 
-    ACCESS_CROSSWORLD("access.crossworld"),
-    ACCESS_OFFLINE("access.offline"),
-    ACCESS_ONLINE("access.online"),
+  CLEAR_SELF("clear.self"),
+  CLEAR_OTHER("clear.other"),
 
-    SPECTATE_CLICK("spectate.click"),
+  ACCESS_CROSSWORLD("access.crossworld"),
+  ACCESS_OFFLINE("access.offline"),
+  ACCESS_ONLINE("access.online"),
 
-    CONTAINER_ANY("container.any"),
-    CONTAINER_SILENT("container.silent"),
-    SEARCH_INVENTORY("search.inventory"),
-    SEARCH_CONTAINER("search.container");
+  SPECTATE_CLICK("spectate.click"),
 
-    private final String permission;
+  CONTAINER_ANY("container.any"),
+  CONTAINER_SILENT("container.silent"),
+  SEARCH_INVENTORY("search.inventory"),
+  SEARCH_CONTAINER("search.container");
 
-    Permissions(String permission) {
-        this.permission = "openinv." + permission;
-    }
+  private final String permission;
 
-    public boolean hasPermission(@NotNull Permissible permissible) {
-        return permissible.hasPermission(permission);
-    }
+  Permissions(String permission) {
+    this.permission = "openinv." + permission;
+  }
+
+  public boolean hasPermission(@NotNull Permissible permissible) {
+    return permissible.hasPermission(permission);
+  }
 
 }

common/src/main/java/com/lishid/openinv/util/ReflectionHelper.java

@@ -25,54 +25,54 @@ import java.lang.reflect.Field;
  */
 public final class ReflectionHelper {
 
-    /**
-     * Grab an {@link Object} stored in a {@link Field} of another {@code Object}.
-     *
-     * <p>This casts the field to the correct class. Any issues will result in a {@code null} return value.
-     *
-     * @param fieldType the {@link Class} of {@code Object} stored in the {@code Field}
-     * @param holder the containing {@code Object}
-     * @param <T> the type of stored {@code Object}
-     * @return the first matching {@code Object} or {@code null} if none match
-     */
-    public static <T> @Nullable T grabObjectByType(final Object holder, final Class<T> fieldType) {
-        Field field = grabFieldByType(holder.getClass(), fieldType);
+  /**
+   * Grab an {@link Object} stored in a {@link Field} of another {@code Object}.
+   *
+   * <p>This casts the field to the correct class. Any issues will result in a {@code null} return value.
+   *
+   * @param fieldType the {@link Class} of {@code Object} stored in the {@code Field}
+   * @param holder the containing {@code Object}
+   * @param <T> the type of stored {@code Object}
+   * @return the first matching {@code Object} or {@code null} if none match
+   */
+  public static <T> @Nullable T grabObjectByType(final Object holder, final Class<T> fieldType) {
+    Field field = grabFieldByType(holder.getClass(), fieldType);
 
-        if (field != null) {
-            try {
-                return fieldType.cast(field.get(holder));
-            } catch (IllegalAccessException ignored) {
-                // Ignore issues obtaining field
-            }
-        }
-
-        return null;
+    if (field != null) {
+      try {
+        return fieldType.cast(field.get(holder));
+      } catch (IllegalAccessException ignored) {
+        // Ignore issues obtaining field
+      }
     }
 
-    /**
-     * Grab a {@link Field} of an {@link Object}
-     *
-     * @param fieldType the {@link Class} of the object
-     * @param holderType the containing {@code Class}
-     * @return the first matching object or {@code null} if none match
-     */
-    public static @Nullable Field grabFieldByType(Class<?> holderType, Class<?> fieldType) {
-        for (Field field : holderType.getDeclaredFields()) {
-            if (fieldType.isAssignableFrom(field.getType())) {
-                field.setAccessible(true);
-                return field;
-            }
-        }
+    return null;
+  }
 
-        if (holderType.getSuperclass() != null) {
-            return grabFieldByType(fieldType, holderType.getSuperclass());
-        }
-
-        return null;
+  /**
+   * Grab a {@link Field} of an {@link Object}
+   *
+   * @param fieldType the {@link Class} of the object
+   * @param holderType the containing {@code Class}
+   * @return the first matching object or {@code null} if none match
+   */
+  public static @Nullable Field grabFieldByType(Class<?> holderType, Class<?> fieldType) {
+    for (Field field : holderType.getDeclaredFields()) {
+      if (fieldType.isAssignableFrom(field.getType())) {
+        field.setAccessible(true);
+        return field;
+      }
     }
 
-    private ReflectionHelper() {
-        throw new IllegalStateException("Cannot create instance of utility class.");
+    if (holderType.getSuperclass() != null) {
+      return grabFieldByType(fieldType, holderType.getSuperclass());
     }
 
+    return null;
+  }
+
+  private ReflectionHelper() {
+    throw new IllegalStateException("Cannot create instance of utility class.");
+  }
+
 }

common/src/main/java/com/lishid/openinv/util/lang/LanguageManager.java

@@ -49,271 +49,278 @@ import java.util.logging.Level;
  */
 public class LanguageManager {
 
-    private final Plugin plugin;
-    private final File folder;
-    private final String defaultLocale;
-    private final Map<String, YamlConfiguration> locales;
+  private final Plugin plugin;
+  private final File folder;
+  private final String defaultLocale;
+  private final Map<String, YamlConfiguration> locales;
 
-    public LanguageManager(@NotNull Plugin plugin, @NotNull String defaultLocale) {
-        this.plugin = plugin;
-        this.defaultLocale = defaultLocale;
-        this.locales = new HashMap<>();
-        this.folder = new File(plugin.getDataFolder(), "locale");
+  public LanguageManager(@NotNull Plugin plugin, @NotNull String defaultLocale) {
+    this.plugin = plugin;
+    this.defaultLocale = defaultLocale;
+    this.locales = new HashMap<>();
+    this.folder = new File(plugin.getDataFolder(), "locale");
 
-        if (!folder.exists() && !folder.mkdirs()) {
-            plugin.getLogger().warning(() -> "Unable to create " + folder.getPath() + "! Languages may not be editable.");
-        }
-
-        reload();
+    if (!folder.exists() && !folder.mkdirs()) {
+      plugin.getLogger().warning(() -> "Unable to create " + folder.getPath() + "! Languages may not be editable.");
     }
 
-    public void reload() {
-        this.locales.clear();
-        getOrLoadLocale(defaultLocale);
+    reload();
+  }
+
+  public void reload() {
+    this.locales.clear();
+    getOrLoadLocale(defaultLocale);
+  }
+
+  private @NotNull YamlConfiguration getOrLoadLocale(@NotNull String locale) {
+    YamlConfiguration loaded = locales.get(locale);
+    if (loaded != null) {
+      return loaded;
     }
 
-    private @NotNull YamlConfiguration getOrLoadLocale(@NotNull String locale) {
-        YamlConfiguration loaded = locales.get(locale);
-        if (loaded != null) {
-            return loaded;
-        }
+    LangLocation lang = bestMatch(locale, null);
 
-        LangLocation lang = bestMatch(locale, null);
-
-        // If a parent was a better match, check if it is already loaded.
-        if (!locale.equals(lang.locale)) {
-            loaded = locales.get(lang.locale);
-            if (loaded != null) {
-                locales.put(locale, loaded);
-                return loaded;
-            }
-        }
-
-        // Load locale config from disk and bundled locale defaults.
-        YamlConfiguration localeConfig = loadLocale(lang);
-
-        // If the locale is not the default locale, also handle any missing translations from the default locale.
-        if (!locale.equals(defaultLocale)) {
-            addTranslationFallthrough(lang, localeConfig);
-
-            if (plugin.getConfig().getBoolean("settings.secret.warn-about-guess-section", true)
-                    && localeConfig.isConfigurationSection("guess")) {
-                // Warn that guess section exists. This should run once per language per server restart
-                // when accessed by a user to hint to server owners that they can make UX improvements.
-                plugin.getLogger().info(() -> "[LanguageManager] Missing translations from " + lang.locale + ".yml! Check the guess section!");
-            }
-        }
-
-        locales.put(locale, localeConfig);
-        locales.put(lang.locale, localeConfig);
-
-        return localeConfig;
+    // If a parent was a better match, check if it is already loaded.
+    if (!locale.equals(lang.locale)) {
+      loaded = locales.get(lang.locale);
+      if (loaded != null) {
+        locales.put(locale, loaded);
+        return loaded;
+      }
     }
 
-    private @NotNull LangLocation bestMatch(@NotNull String locale, @Nullable LangLocation initial) {
-        File file = new File(folder, locale + ".yml");
-        InputStream bundled = plugin.getResource("locale/" + locale + ".yml");
+    // Load locale config from disk and bundled locale defaults.
+    YamlConfiguration localeConfig = loadLocale(lang);
 
-        if (file.exists() || bundled != null) {
-            return new LangLocation(locale, file, bundled);
-        }
+    // If the locale is not the default locale, also handle any missing translations from the default locale.
+    if (!locale.equals(defaultLocale)) {
+      addTranslationFallthrough(lang, localeConfig);
 
-        if (initial == null) {
-            initial = new LangLocation(locale, file, null);
-        }
-
-        int lastSeparator = locale.lastIndexOf('_');
-
-        // Must be at least some content before separator.
-        if (lastSeparator < 1) {
-            return initial;
-        }
-
-        return bestMatch(locale.substring(0, lastSeparator), initial);
+      if (plugin.getConfig().getBoolean("settings.secret.warn-about-guess-section", true)
+          && localeConfig.isConfigurationSection("guess")) {
+        // Warn that guess section exists. This should run once per language per server restart
+        // when accessed by a user to hint to server owners that they can make UX improvements.
+        plugin.getLogger().info(() -> "[LanguageManager] Missing translations from " + lang.locale + ".yml! Check the guess section!");
+      }
     }
 
-    private @NotNull YamlConfiguration loadLocale(@NotNull LangLocation lang) {
-        YamlConfiguration localeConfigDefaults;
-        if (lang.bundled == null) {
-            localeConfigDefaults = new YamlConfiguration();
-        } else {
-            try (BufferedReader reader = new BufferedReader(new InputStreamReader(lang.bundled, StandardCharsets.UTF_8))) {
-                localeConfigDefaults = YamlConfiguration.loadConfiguration(reader);
-            } catch (IOException e) {
-                plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to load resource " + lang.locale + ".yml");
-                localeConfigDefaults = new YamlConfiguration();
-            }
-        }
+    locales.put(locale, localeConfig);
+    locales.put(lang.locale, localeConfig);
 
-        if (!lang.file.exists()) {
-            // If the file does not exist on disk, save bundled defaults.
-            try {
-                localeConfigDefaults.save(lang.file);
-            } catch (IOException e) {
-                plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to save resource " + lang.locale + ".yml");
-            }
-            // Return loaded bundled locale.
-            return localeConfigDefaults;
-        }
+    return localeConfig;
+  }
 
-        // If the file does exist on disk, load it.
-        YamlConfiguration localeConfig = YamlConfiguration.loadConfiguration(lang.file);
-        // Check for missing translations from the bundled file.
-        List<String> newKeys = getMissingKeys(localeConfigDefaults, localeConfig::isSet);
+  private @NotNull LangLocation bestMatch(@NotNull String locale, @Nullable LangLocation initial) {
+    File file = new File(folder, locale + ".yml");
+    InputStream bundled = plugin.getResource("locale/" + locale + ".yml");
 
-        if (newKeys.isEmpty()) {
-            return localeConfig;
-        }
-
-        // Get guess section for missing keys.
-        ConfigurationSection guess = localeConfig.getConfigurationSection("guess");
-
-        for (String newKey : newKeys) {
-            // Set all missing keys to defaults.
-            localeConfig.set(newKey, localeConfigDefaults.get(newKey));
-
-            // Delete relevant guess keys in case this is a new translation.
-            if (guess != null) {
-                guess.set(newKey, null);
-            }
-        }
-
-        // If guess section is empty, delete it.
-        if (guess != null && guess.getKeys(false).isEmpty()) {
-            localeConfig.set("guess", null);
-        }
-
-        plugin.getLogger().info(() -> "[LanguageManager] Added new translation keys to " + lang.locale + ".yml: " + String.join(", ", newKeys));
-
-        // Write new keys to disk.
-        try {
-            localeConfig.save(lang.file);
-        } catch (IOException e) {
-            plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to save resource " + lang.locale + ".yml");
-        }
-
-        return localeConfig;
+    if (file.exists() || bundled != null) {
+      return new LangLocation(locale, file, bundled);
     }
 
-    private void addTranslationFallthrough(@NotNull LangLocation location, @NotNull YamlConfiguration localeConfig) {
-        YamlConfiguration defaultLocaleConfig = locales.get(defaultLocale);
-
-        // Get missing keys. Keys that already have a guess value are not new and don't need to trigger another write.
-        List<String> missingKeys = getMissingKeys(
-                defaultLocaleConfig,
-                key -> localeConfig.isSet(key) || localeConfig.isSet("guess." + key));
-
-        if (!missingKeys.isEmpty()) {
-            // Set up guess section for missing keys.
-            for (String key : missingKeys) {
-                localeConfig.set("guess." + key, defaultLocaleConfig.get(key));
-            }
-
-            // Write modified guess section to disk.
-            try {
-                localeConfig.save(location.file);
-            } catch (IOException e) {
-                plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to save resource " + location.locale + ".yml");
-            }
-        }
-
-        // Fall through to default locale.
-        localeConfig.setDefaults(defaultLocaleConfig);
+    if (initial == null) {
+      initial = new LangLocation(locale, file, null);
     }
 
-    private @NotNull List<String> getMissingKeys(
-            @NotNull Configuration configurationDefault,
-            @NotNull Predicate<String> nodeSetPredicate) {
-        List<String> missingKeys = new ArrayList<>();
-        for (String key : configurationDefault.getKeys(true)) {
-            if (!configurationDefault.isConfigurationSection(key) && !nodeSetPredicate.test(key)) {
-                // Missing keys are non-section keys that fail the predicate.
-                missingKeys.add(key);
-            }
-        }
-        return missingKeys;
+    int lastSeparator = locale.lastIndexOf('_');
+
+    // Must be at least some content before separator.
+    if (lastSeparator < 1) {
+      return initial;
     }
 
-    public @Nullable String getValue(@NotNull String key, @Nullable String locale) {
-        String value = getOrLoadLocale(locale == null ? defaultLocale : locale.toLowerCase(Locale.ENGLISH)).getString(key);
-        if (value == null || value.isBlank()) {
-            return null;
-        }
+    return bestMatch(locale.substring(0, lastSeparator), initial);
+  }
 
-        value = ChatColor.translateAlternateColorCodes('&', value);
-
-        return value;
+  private @NotNull YamlConfiguration loadLocale(@NotNull LangLocation lang) {
+    YamlConfiguration localeConfigDefaults;
+    if (lang.bundled == null) {
+      localeConfigDefaults = new YamlConfiguration();
+    } else {
+      try (BufferedReader reader = new BufferedReader(new InputStreamReader(lang.bundled, StandardCharsets.UTF_8))) {
+        localeConfigDefaults = YamlConfiguration.loadConfiguration(reader);
+      } catch (IOException e) {
+        plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to load resource " + lang.locale + ".yml");
+        localeConfigDefaults = new YamlConfiguration();
+      }
     }
 
-    public @Nullable String getValue(@NotNull String key, @Nullable String locale, Replacement @NotNull ... replacements) {
-        String value = getValue(key, locale);
-
-        if (value == null) {
-            return null;
-        }
-
-        for (Replacement replacement : replacements) {
-            value = value.replace(replacement.placeholder(), replacement.value());
-        }
-
-        return value;
+    if (!lang.file.exists()) {
+      // If the file does not exist on disk, save bundled defaults.
+      try {
+        localeConfigDefaults.save(lang.file);
+      } catch (IOException e) {
+        plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to save resource " + lang.locale + ".yml");
+      }
+      // Return loaded bundled locale.
+      return localeConfigDefaults;
     }
 
-    public @Nullable String getLocalizedMessage(@NotNull CommandSender sender, @NotNull String key) {
-        return getValue(key, getLocale(sender));
+    // If the file does exist on disk, load it.
+    YamlConfiguration localeConfig = YamlConfiguration.loadConfiguration(lang.file);
+    // Check for missing translations from the bundled file.
+    List<String> newKeys = getMissingKeys(localeConfigDefaults, localeConfig::isSet);
+
+    if (newKeys.isEmpty()) {
+      return localeConfig;
     }
 
-    public @Nullable String getLocalizedMessage(
-        @NotNull CommandSender sender,
-        @NotNull String key,
-        Replacement @NotNull ... replacements) {
-        return getValue(key, getLocale(sender), replacements);
+    // Get guess section for missing keys.
+    ConfigurationSection guess = localeConfig.getConfigurationSection("guess");
+
+    for (String newKey : newKeys) {
+      // Set all missing keys to defaults.
+      localeConfig.set(newKey, localeConfigDefaults.get(newKey));
+
+      // Delete relevant guess keys in case this is a new translation.
+      if (guess != null) {
+        guess.set(newKey, null);
+      }
     }
 
-    private @NotNull String getLocale(@NotNull CommandSender sender) {
-        if (sender instanceof Player) {
-            return ((Player) sender).getLocale();
-        } else {
-            return plugin.getConfig().getString("settings.locale", "en");
-        }
+    // If guess section is empty, delete it.
+    if (guess != null && guess.getKeys(false).isEmpty()) {
+      localeConfig.set("guess", null);
     }
 
-    public void sendMessage(@NotNull CommandSender sender, @NotNull String key) {
-        String message = getLocalizedMessage(sender, key);
+    plugin.getLogger().info(() -> "[LanguageManager] Added new translation keys to " + lang.locale + ".yml: " + String.join(", ", newKeys));
 
-        if (message != null && !message.isEmpty()) {
-            sender.sendMessage(message);
-        }
+    // Write new keys to disk.
+    try {
+      localeConfig.save(lang.file);
+    } catch (IOException e) {
+      plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to save resource " + lang.locale + ".yml");
     }
 
-    public void sendMessage(@NotNull CommandSender sender, @NotNull String key, Replacement @NotNull... replacements) {
-        String message = getLocalizedMessage(sender, key, replacements);
+    return localeConfig;
+  }
 
-        if (message != null && !message.isEmpty()) {
-            sender.sendMessage(message);
-        }
+  private void addTranslationFallthrough(@NotNull LangLocation location, @NotNull YamlConfiguration localeConfig) {
+    YamlConfiguration defaultLocaleConfig = locales.get(defaultLocale);
+
+    // Get missing keys. Keys that already have a guess value are not new and don't need to trigger another write.
+    List<String> missingKeys = getMissingKeys(
+        defaultLocaleConfig,
+        key -> localeConfig.isSet(key) || localeConfig.isSet("guess." + key)
+    );
+
+    if (!missingKeys.isEmpty()) {
+      // Set up guess section for missing keys.
+      for (String key : missingKeys) {
+        localeConfig.set("guess." + key, defaultLocaleConfig.get(key));
+      }
+
+      // Write modified guess section to disk.
+      try {
+        localeConfig.save(location.file);
+      } catch (IOException e) {
+        plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to save resource " + location.locale + ".yml");
+      }
     }
 
-    public void sendSystemMessage(@NotNull Player player, @NotNull String key) {
-        String message = getLocalizedMessage(player, key);
+    // Fall through to default locale.
+    localeConfig.setDefaults(defaultLocaleConfig);
+  }
 
-        if (message == null) {
-            return;
-        }
+  private @NotNull List<String> getMissingKeys(
+      @NotNull Configuration configurationDefault,
+      @NotNull Predicate<String> nodeSetPredicate
+  ) {
+    List<String> missingKeys = new ArrayList<>();
+    for (String key : configurationDefault.getKeys(true)) {
+      if (!configurationDefault.isConfigurationSection(key) && !nodeSetPredicate.test(key)) {
+        // Missing keys are non-section keys that fail the predicate.
+        missingKeys.add(key);
+      }
+    }
+    return missingKeys;
+  }
 
-        int newline = message.indexOf('\n');
-        if (newline != -1) {
-            // No newlines in action bar chat.
-            message = message.substring(0, newline);
-        }
-
-        if (message.isEmpty()) {
-            return;
-        }
-
-        player.spigot().sendMessage(ChatMessageType.ACTION_BAR, TextComponent.fromLegacy(message));
+  public @Nullable String getValue(@NotNull String key, @Nullable String locale) {
+    String value = getOrLoadLocale(locale == null ? defaultLocale : locale.toLowerCase(Locale.ENGLISH)).getString(key);
+    if (value == null || value.isBlank()) {
+      return null;
     }
 
-    private record LangLocation(@NotNull String locale, @NotNull File file, @Nullable InputStream bundled) {}
+    value = ChatColor.translateAlternateColorCodes('&', value);
+
+    return value;
+  }
+
+  public @Nullable String getValue(
+      @NotNull String key,
+      @Nullable String locale,
+      Replacement @NotNull ... replacements
+  ) {
+    String value = getValue(key, locale);
+
+    if (value == null) {
+      return null;
+    }
+
+    for (Replacement replacement : replacements) {
+      value = value.replace(replacement.placeholder(), replacement.value());
+    }
+
+    return value;
+  }
+
+  public @Nullable String getLocalizedMessage(@NotNull CommandSender sender, @NotNull String key) {
+    return getValue(key, getLocale(sender));
+  }
+
+  public @Nullable String getLocalizedMessage(
+      @NotNull CommandSender sender,
+      @NotNull String key,
+      Replacement @NotNull ... replacements
+  ) {
+    return getValue(key, getLocale(sender), replacements);
+  }
+
+  private @NotNull String getLocale(@NotNull CommandSender sender) {
+    if (sender instanceof Player player) {
+      return player.getLocale();
+    } else {
+      return plugin.getConfig().getString("settings.locale", "en");
+    }
+  }
+
+  public void sendMessage(@NotNull CommandSender sender, @NotNull String key) {
+    String message = getLocalizedMessage(sender, key);
+
+    if (message != null && !message.isEmpty()) {
+      sender.sendMessage(message);
+    }
+  }
+
+  public void sendMessage(@NotNull CommandSender sender, @NotNull String key, Replacement @NotNull ... replacements) {
+    String message = getLocalizedMessage(sender, key, replacements);
+
+    if (message != null && !message.isEmpty()) {
+      sender.sendMessage(message);
+    }
+  }
+
+  public void sendSystemMessage(@NotNull Player player, @NotNull String key) {
+    String message = getLocalizedMessage(player, key);
+
+    if (message == null) {
+      return;
+    }
+
+    int newline = message.indexOf('\n');
+    if (newline != -1) {
+      // No newlines in action bar chat.
+      message = message.substring(0, newline);
+    }
+
+    if (message.isEmpty()) {
+      return;
+    }
+
+    player.spigot().sendMessage(ChatMessageType.ACTION_BAR, TextComponent.fromLegacy(message));
+  }
+
+  private record LangLocation(@NotNull String locale, @NotNull File file, @Nullable InputStream bundled) {}
 
 }

gradle.properties

@@ -1,6 +1,6 @@
 # Project meta
 group=com.lishid.openinv
-version=5.1.8
+version=5.1.13
 description=A Bukkit plugin for opening normally-inaccessible inventories.
 
 # Gradle configuration

gradle/libs.versions.toml

@@ -1,17 +1,26 @@
 [versions]
-spigotapi = "1.21.4-R0.1-SNAPSHOT"
-specialsource = "1.11.4"
+spigotapi = "1.21.5-R0.1-SNAPSHOT"
+specialsource = "1.11.5"
 planarwrappers = "3.3.0"
 annotations = "26.0.2"
-paperweight = "2.0.0-beta.14"
-shadow = "8.3.6"
+paperweight = "2.0.0-beta.17"
+shadow = "8.3.8"
+folia-scheduler-wrapper = "v0.0.3"
+errorprone-core = "2.39.0"
+errorprone-gradle = "4.2.0"
+slf4j = "2.0.17"
 
 [libraries]
 spigotapi = { module = "org.spigotmc:spigot-api", version.ref = "spigotapi" }
 specialsource = { module = "net.md-5:SpecialSource", version.ref = "specialsource" }
 planarwrappers = { module = "com.github.jikoo:planarwrappers", version.ref = "planarwrappers" }
 annotations = { module = "org.jetbrains:annotations", version.ref = "annotations" }
+folia-scheduler-wrapper = { module = "com.github.NahuLD.folia-scheduler-wrapper:folia-scheduler-wrapper", version.ref = "folia-scheduler-wrapper" }
+errorprone-core = { module = "com.google.errorprone:error_prone_core", version.ref = "errorprone-core" }
+errorprone-gradle = { module = "net.ltgt.gradle:gradle-errorprone-plugin", version.ref = "errorprone-gradle" }
+slf4j-api = { module = "org.slf4j:slf4j-api", version.ref = "slf4j" }
 
 [plugins]
 paperweight = { id = "io.papermc.paperweight.userdev", version.ref = "paperweight" }
-shadow = { id = "com.gradleup.shadow", version.ref = "shadow" }
+shadow = { id = "com.gradleup.shadow", version.ref = "shadow" }
+errorprone-gradle = { id = "net.ltgt.errorprone", version.ref = "errorprone-gradle" }

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,7 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.12-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.14-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

gradlew

@@ -15,6 +15,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 
 ##############################################################################
 #
@@ -55,7 +57,7 @@
 #       Darwin, MinGW, and NonStop.
 #
 #   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       https://github.com/gradle/gradle/blob/HEAD/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
 #       within the Gradle project.
 #
 #       You can find Gradle at https://github.com/gradle/gradle/.
@@ -80,13 +82,11 @@ do
     esac
 done
 
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
-
-APP_NAME="Gradle"
+# This is normally unused
+# shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
-
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd -P "${APP_HOME:-./}" > /dev/null && printf '%s\n' "$PWD" ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD=maximum
@@ -133,22 +133,29 @@ location of your Java installation."
     fi
 else
     JAVACMD=java
-    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
 Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
+    fi
 fi
 
 # Increase the maximum file descriptors if we can.
 if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
     case $MAX_FD in #(
       max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
         MAX_FD=$( ulimit -H -n ) ||
             warn "Could not query maximum file descriptor limit"
     esac
     case $MAX_FD in  #(
       '' | soft) :;; #(
       *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
         ulimit -n "$MAX_FD" ||
             warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
@@ -193,11 +200,15 @@ if "$cygwin" || "$msys" ; then
     done
 fi
 
-# Collect all arguments for the java command;
-#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
-#     shell script including quotes and variable substitutions, so put them in
-#     double quotes to make sure that they get re-expanded; and
-#   * put everything else in single quotes, so that it's not re-expanded.
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
 
 set -- \
         "-Dorg.gradle.appname=$APP_BASE_NAME" \
@@ -205,6 +216,12 @@ set -- \
         org.gradle.wrapper.GradleWrapperMain \
         "$@"
 
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
 # Use "xargs" to parse quoted args.
 #
 # With -n1 it outputs one arg per line, with the quotes and backslashes removed.

gradlew.bat

@@ -13,8 +13,10 @@
 @rem See the License for the specific language governing permissions and
 @rem limitations under the License.
 @rem
+@rem SPDX-License-Identifier: Apache-2.0
+@rem
 
-@if "%DEBUG%" == "" @echo off
+@if "%DEBUG%"=="" @echo off
 @rem ##########################################################################
 @rem
 @rem  Gradle startup script for Windows
@@ -25,7 +27,8 @@
 if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
-if "%DIRNAME%" == "" set DIRNAME=.
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
@@ -40,13 +43,13 @@ if defined JAVA_HOME goto findJavaFromJavaHome
 
 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto execute
+if %ERRORLEVEL% equ 0 goto execute
 
-echo.
-echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail
 
@@ -56,11 +59,11 @@ set JAVA_EXE=%JAVA_HOME%/bin/java.exe
 
 if exist "%JAVA_EXE%" goto execute
 
-echo.
-echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
-echo.
-echo Please set the JAVA_HOME variable in your environment to match the
-echo location of your Java installation.
+echo. 1>&2
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
 
 goto fail
 
@@ -75,13 +78,15 @@ set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
 
 :end
 @rem End local scope for the variables with windows NT shell
-if "%ERRORLEVEL%"=="0" goto mainEnd
+if %ERRORLEVEL% equ 0 goto mainEnd
 
 :fail
 rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
 rem the _cmd.exe /c_ return code!
-if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
-exit /b 1
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
 
 :mainEnd
 if "%OS%"=="Windows_NT" endlocal

internal/common/build.gradle.kts

@@ -18,8 +18,8 @@ plugins {
 configurations.all {
   resolutionStrategy.capabilitiesResolution.withCapability("org.spigotmc:spigot-api") {
     val paper = candidates.firstOrNull {
-      it.id.let {
-        id -> id is ModuleComponentIdentifier && id.module == "paper-api"
+      it.id.let { id ->
+        id is ModuleComponentIdentifier && id.module == "paper-api"
       }
     }
     if (paper != null) {
@@ -33,7 +33,7 @@ dependencies {
   implementation(project(":openinvapi"))
   implementation(project(":openinvcommon"))
 
-  paperweight.paperDevBundle("1.21.4-R0.1-SNAPSHOT")
+  paperweight.paperDevBundle("1.21.8-R0.1-SNAPSHOT")
 }
 
 val spigot = tasks.register<ShadowJar>("spigotRelocations") {

internal/common/src/main/java/com/lishid/openinv/internal/common/container/AnySilentContainer.java

@@ -27,6 +27,7 @@ import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.server.level.ServerPlayerGameMode;
 import net.minecraft.world.MenuProvider;
 import net.minecraft.world.SimpleMenuProvider;
+import net.minecraft.world.entity.Entity;
 import net.minecraft.world.inventory.ChestMenu;
 import net.minecraft.world.inventory.MenuType;
 import net.minecraft.world.inventory.PlayerEnderChestContainer;
@@ -52,159 +53,164 @@ import java.util.logging.Logger;
 
 public class AnySilentContainer extends AnySilentContainerBase {
 
-    private final @NotNull Logger logger;
-    private final @NotNull LanguageManager lang;
-    private @Nullable Field serverPlayerGameModeGameType;
+  private final @NotNull Logger logger;
+  private final @NotNull LanguageManager lang;
+  private @Nullable Field serverPlayerGameModeGameType;
 
-    public AnySilentContainer(@NotNull Logger logger, @NotNull LanguageManager lang) {
-        this.logger = logger;
-        this.lang = lang;
-        try {
-            try {
-                this.serverPlayerGameModeGameType = ServerPlayerGameMode.class.getDeclaredField("gameModeForPlayer");
-                this.serverPlayerGameModeGameType.setAccessible(true);
-            } catch (NoSuchFieldException e) {
-                logger.warning("The field ServerPlayerGameMode#gameModeForPlayer is no longer present!");
-                logger.warning("Please report this at https://github.com/Jikoo/OpenInv/issues");
-                logger.warning("Attempting to fall through using reflection. Please verify that SilentContainer does not fail.");
-                // N.B. gameModeForPlayer is (for now) declared before previousGameModeForPlayer so silent shouldn't break.
-                this.serverPlayerGameModeGameType = ReflectionHelper.grabFieldByType(ServerPlayerGameMode.class, GameType.class);
-            }
-        } catch (SecurityException e) {
-            logger.warning("Unable to directly write player game mode! SilentContainer will fail.");
-            logger.log(java.util.logging.Level.WARNING, "Error obtaining GameType field", e);
-        }
+  public AnySilentContainer(@NotNull Logger logger, @NotNull LanguageManager lang) {
+    this.logger = logger;
+    this.lang = lang;
+    try {
+      try {
+        this.serverPlayerGameModeGameType = ServerPlayerGameMode.class.getDeclaredField("gameModeForPlayer");
+        this.serverPlayerGameModeGameType.setAccessible(true);
+      } catch (NoSuchFieldException e) {
+        logger.warning("The field ServerPlayerGameMode#gameModeForPlayer is no longer present!");
+        logger.warning("Please report this at https://github.com/Jikoo/OpenInv/issues");
+        logger.warning("Attempting to fall through using reflection. Please verify that SilentContainer does not fail.");
+        // N.B. gameModeForPlayer is (for now) declared before previousGameModeForPlayer so silent shouldn't break.
+        this.serverPlayerGameModeGameType = ReflectionHelper.grabFieldByType(ServerPlayerGameMode.class, GameType.class);
+      }
+    } catch (SecurityException e) {
+      logger.warning("Unable to directly write player game mode! SilentContainer will fail.");
+      logger.log(java.util.logging.Level.WARNING, "Error obtaining GameType field", e);
+    }
+  }
+
+  @Override
+  public boolean activateContainer(
+      @NotNull final Player bukkitPlayer,
+      final boolean silentchest,
+      @NotNull final org.bukkit.block.Block bukkitBlock
+  ) {
+
+    // Silent ender chest is API-only
+    if (silentchest && bukkitBlock.getType() == Material.ENDER_CHEST) {
+      bukkitPlayer.openInventory(bukkitPlayer.getEnderChest());
+      bukkitPlayer.incrementStatistic(Statistic.ENDERCHEST_OPENED);
+      return true;
     }
 
-    @Override
-    public boolean activateContainer(
-            @NotNull final Player bukkitPlayer,
-            final boolean silentchest,
-            @NotNull final org.bukkit.block.Block bukkitBlock) {
+    ServerPlayer player = PlayerManager.getHandle(bukkitPlayer);
 
-        // Silent ender chest is API-only
-        if (silentchest && bukkitBlock.getType() == Material.ENDER_CHEST) {
-            bukkitPlayer.openInventory(bukkitPlayer.getEnderChest());
-            bukkitPlayer.incrementStatistic(Statistic.ENDERCHEST_OPENED);
-            return true;
-        }
+    final net.minecraft.world.level.Level level = ((Entity) player).level();
+    final BlockPos blockPos = new BlockPos(bukkitBlock.getX(), bukkitBlock.getY(), bukkitBlock.getZ());
+    final BlockEntity blockEntity = level.getBlockEntity(blockPos);
 
-        ServerPlayer player = PlayerManager.getHandle(bukkitPlayer);
+    if (blockEntity == null) {
+      return false;
+    }
 
-        final net.minecraft.world.level.Level level = player.level();
-        final BlockPos blockPos = new BlockPos(bukkitBlock.getX(), bukkitBlock.getY(), bukkitBlock.getZ());
-        final BlockEntity blockEntity = level.getBlockEntity(blockPos);
-
-        if (blockEntity == null) {
-            return false;
-        }
-
-        if (blockEntity instanceof EnderChestBlockEntity enderChestTile) {
-            // Anychest ender chest. See net.minecraft.world.level.block.EnderChestBlock
-            PlayerEnderChestContainer enderChest = player.getEnderChestInventory();
-            enderChest.setActiveChest(enderChestTile);
-            player.openMenu(new SimpleMenuProvider((containerCounter, playerInventory, ignored) -> {
+    if (blockEntity instanceof EnderChestBlockEntity enderChestTile) {
+      // Anychest ender chest. See net.minecraft.world.level.block.EnderChestBlock
+      PlayerEnderChestContainer enderChest = player.getEnderChestInventory();
+      enderChest.setActiveChest(enderChestTile);
+      player.openMenu(
+          new SimpleMenuProvider(
+              (containerCounter, playerInventory, ignored) -> {
                 MenuType<?> containers = OpenChestMenu.getChestMenuType(enderChest.getContainerSize());
                 int rows = enderChest.getContainerSize() / 9;
                 return new ChestMenu(containers, containerCounter, playerInventory, enderChest, rows);
-            }, Component.translatable("container.enderchest")));
-            bukkitPlayer.incrementStatistic(Statistic.ENDERCHEST_OPENED);
-            return true;
-        }
-
-        if (!(blockEntity instanceof MenuProvider menuProvider)) {
-            return false;
-        }
-
-        BlockState blockState = level.getBlockState(blockPos);
-        Block block = blockState.getBlock();
-
-        if (block instanceof ChestBlock chestBlock) {
-
-            // boolean flag: do not check if chest is blocked
-            menuProvider = chestBlock.getMenuProvider(blockState, level, blockPos, true);
-
-            if (menuProvider == null) {
-                lang.sendSystemMessage(bukkitPlayer, "messages.error.lootNotGenerated");
-                return false;
-            }
-
-            if (block instanceof TrappedChestBlock) {
-                bukkitPlayer.incrementStatistic(Statistic.TRAPPED_CHEST_TRIGGERED);
-            } else {
-                bukkitPlayer.incrementStatistic(Statistic.CHEST_OPENED);
-            }
-        }
-
-        if (block instanceof ShulkerBoxBlock) {
-            bukkitPlayer.incrementStatistic(Statistic.SHULKER_BOX_OPENED);
-        }
-
-        if (block instanceof BarrelBlock) {
-            bukkitPlayer.incrementStatistic(Statistic.OPEN_BARREL);
-        }
-
-        // AnyChest only - SilentChest not active, container unsupported, or unnecessary.
-        if (!silentchest || player.gameMode.getGameModeForPlayer() == GameType.SPECTATOR) {
-            player.openMenu(menuProvider);
-            return true;
-        }
-
-        // SilentChest requires access to setting players' game mode directly.
-        if (this.serverPlayerGameModeGameType == null) {
-            return false;
-        }
-
-        if (blockEntity instanceof RandomizableContainerBlockEntity lootable) {
-            if (lootable.lootTable != null) {
-                lang.sendSystemMessage(bukkitPlayer, "messages.error.lootNotGenerated");
-                return false;
-            }
-        }
-
-        GameType gameType = player.gameMode.getGameModeForPlayer();
-        this.forceGameType(player, GameType.SPECTATOR);
-        player.openMenu(menuProvider);
-        this.forceGameType(player, gameType);
-        return true;
+              }, Component.translatable("container.enderchest")
+          )
+      );
+      bukkitPlayer.incrementStatistic(Statistic.ENDERCHEST_OPENED);
+      return true;
     }
 
-    @Override
-    public void deactivateContainer(@NotNull final Player bukkitPlayer) {
-        if (this.serverPlayerGameModeGameType == null || bukkitPlayer.getGameMode() == GameMode.SPECTATOR) {
-            return;
-        }
-
-        ServerPlayer player = PlayerManager.getHandle(bukkitPlayer);
-
-        // Force game mode change without informing plugins or players.
-        // Regular game mode set calls GameModeChangeEvent and is cancellable.
-        GameType gameType = player.gameMode.getGameModeForPlayer();
-        this.forceGameType(player, GameType.SPECTATOR);
-
-        // ServerPlayer#closeContainer cannot be called without entering an
-        // infinite loop because this method is called during inventory close.
-        // From ServerPlayer#closeContainer -> CraftEventFactory#handleInventoryCloseEvent
-        player.containerMenu.transferTo(player.inventoryMenu, player.getBukkitEntity());
-        // From ServerPlayer#closeContainer
-        player.doCloseContainer();
-        // Regular inventory close will handle the rest - packet sending, etc.
-
-        // Revert forced game mode.
-        this.forceGameType(player, gameType);
+    if (!(blockEntity instanceof MenuProvider menuProvider)) {
+      return false;
     }
 
-    private void forceGameType(final ServerPlayer player, final GameType gameMode) {
-        if (this.serverPlayerGameModeGameType == null) {
-            // No need to warn repeatedly, error on startup and lack of function should be enough.
-            return;
-        }
-        try {
-            this.serverPlayerGameModeGameType.setAccessible(true);
-            this.serverPlayerGameModeGameType.set(player.gameMode, gameMode);
-        } catch (IllegalArgumentException | IllegalAccessException e) {
-            logger.log(java.util.logging.Level.WARNING, "Error bypassing GameModeChangeEvent", e);
-        }
+    BlockState blockState = level.getBlockState(blockPos);
+    Block block = blockState.getBlock();
+
+    if (block instanceof ChestBlock chestBlock) {
+
+      // boolean flag: do not check if chest is blocked
+      menuProvider = chestBlock.getMenuProvider(blockState, level, blockPos, true);
+
+      if (menuProvider == null) {
+        lang.sendSystemMessage(bukkitPlayer, "messages.error.lootNotGenerated");
+        return false;
+      }
+
+      if (block instanceof TrappedChestBlock) {
+        bukkitPlayer.incrementStatistic(Statistic.TRAPPED_CHEST_TRIGGERED);
+      } else {
+        bukkitPlayer.incrementStatistic(Statistic.CHEST_OPENED);
+      }
     }
 
+    if (block instanceof ShulkerBoxBlock) {
+      bukkitPlayer.incrementStatistic(Statistic.SHULKER_BOX_OPENED);
+    }
+
+    if (block instanceof BarrelBlock) {
+      bukkitPlayer.incrementStatistic(Statistic.OPEN_BARREL);
+    }
+
+    // AnyChest only - SilentChest not active, container unsupported, or unnecessary.
+    if (!silentchest || player.gameMode.getGameModeForPlayer() == GameType.SPECTATOR) {
+      player.openMenu(menuProvider);
+      return true;
+    }
+
+    // SilentChest requires access to setting players' game mode directly.
+    if (this.serverPlayerGameModeGameType == null) {
+      return false;
+    }
+
+    if (blockEntity instanceof RandomizableContainerBlockEntity lootable) {
+      if (lootable.lootTable != null) {
+        lang.sendSystemMessage(bukkitPlayer, "messages.error.lootNotGenerated");
+        return false;
+      }
+    }
+
+    GameType gameType = player.gameMode.getGameModeForPlayer();
+    this.forceGameType(player, GameType.SPECTATOR);
+    player.openMenu(menuProvider);
+    this.forceGameType(player, gameType);
+    return true;
+  }
+
+  @Override
+  public void deactivateContainer(@NotNull final Player bukkitPlayer) {
+    if (this.serverPlayerGameModeGameType == null || bukkitPlayer.getGameMode() == GameMode.SPECTATOR) {
+      return;
+    }
+
+    ServerPlayer player = PlayerManager.getHandle(bukkitPlayer);
+
+    // Force game mode change without informing plugins or players.
+    // Regular game mode set calls GameModeChangeEvent and is cancellable.
+    GameType gameType = player.gameMode.getGameModeForPlayer();
+    this.forceGameType(player, GameType.SPECTATOR);
+
+    // ServerPlayer#closeContainer cannot be called without entering an
+    // infinite loop because this method is called during inventory close.
+    // From ServerPlayer#closeContainer -> CraftEventFactory#handleInventoryCloseEvent
+    player.containerMenu.transferTo(player.inventoryMenu, player.getBukkitEntity());
+    // From ServerPlayer#closeContainer
+    player.doCloseContainer();
+    // Regular inventory close will handle the rest - packet sending, etc.
+
+    // Revert forced game mode.
+    this.forceGameType(player, gameType);
+  }
+
+  private void forceGameType(final ServerPlayer player, final GameType gameMode) {
+    if (this.serverPlayerGameModeGameType == null) {
+      // No need to warn repeatedly, error on startup and lack of function should be enough.
+      return;
+    }
+    try {
+      this.serverPlayerGameModeGameType.setAccessible(true);
+      this.serverPlayerGameModeGameType.set(player.gameMode, gameMode);
+    } catch (IllegalArgumentException | IllegalAccessException e) {
+      logger.log(java.util.logging.Level.WARNING, "Error bypassing GameModeChangeEvent", e);
+    }
+  }
+
 }

internal/common/src/main/java/com/lishid/openinv/internal/common/container/OpenEnderChest.java

@@ -71,9 +71,6 @@ public class OpenEnderChest implements Container, StackedContentsCompatible, Int
     items = activeItems;
   }
 
-  @Override
-  public void setPlayerOffline() {}
-
   @Override
   public @NotNull org.bukkit.entity.Player getPlayer() {
     return owner.getBukkitEntity();

internal/common/src/main/java/com/lishid/openinv/internal/common/container/OpenInventory.java

@@ -16,6 +16,7 @@ import com.lishid.openinv.internal.common.container.slot.ContentViewOnly;
 import com.lishid.openinv.internal.common.container.slot.SlotViewOnly;
 import com.lishid.openinv.internal.common.container.slot.placeholder.Placeholders;
 import com.lishid.openinv.internal.common.player.PlayerManager;
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
 import net.minecraft.ChatFormatting;
 import net.minecraft.core.NonNullList;
 import net.minecraft.network.chat.Component;
@@ -38,15 +39,17 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.List;
+import java.util.Map;
 
 public class OpenInventory implements Container, InternalOwned<ServerPlayer>, ISpecialPlayerInventory {
 
-  private final List<Content> slots;
+  protected final List<Content> slots;
   private final int size;
-  private ServerPlayer owner;
+  protected ServerPlayer owner;
   private int maxStackSize = 99;
-  private CraftInventory bukkitEntity;
+  protected CraftInventory bukkitEntity;
   public List<HumanEntity> transaction = new ArrayList<>();
 
   public OpenInventory(@NotNull org.bukkit.entity.Player bukkitPlayer) {
@@ -60,16 +63,15 @@ public class OpenInventory implements Container, InternalOwned<ServerPlayer>, IS
     setupSlots();
   }
 
-  private void setupSlots() {
+  protected void setupSlots() {
     // Top of inventory: Regular contents.
     int nextIndex = addMainInventory();
 
     // If inventory is expected size, we can arrange slots to be pretty.
     Inventory ownerInv = owner.getInventory();
-    if (ownerInv.items.size() == 36
-        && ownerInv.armor.size() == 4
-        && ownerInv.offhand.size() == 1
-        && owner.inventoryMenu.getCraftSlots().getContainerSize() == 4) {
+    if (ownerInv.getNonEquipmentItems().size() == 36
+        && owner.inventoryMenu.getCraftSlots().getContainerSize() == 4
+        && (Inventory.EQUIPMENT_SLOT_MAPPING.size() == 5 || Inventory.EQUIPMENT_SLOT_MAPPING.size() == 7)) {
       // Armor slots: Bottom left.
       addArmor(36);
       // Off-hand: Below chestplate.
@@ -95,7 +97,7 @@ public class OpenInventory implements Container, InternalOwned<ServerPlayer>, IS
   }
 
   private int addMainInventory() {
-    int listSize = owner.getInventory().items.size();
+    int listSize = owner.getInventory().getNonEquipmentItems().size();
     // Hotbar slots are 0-8. We want those to appear on the bottom of the inventory like a normal player inventory,
     // so everything else needs to move up a row.
     int hotbarDiff = listSize - 9;
@@ -110,61 +112,50 @@ public class OpenInventory implements Container, InternalOwned<ServerPlayer>, IS
         invIndex = localIndex - hotbarDiff;
       }
 
-      slots.set(localIndex, new ContentList(owner, invIndex, type) {
-        @Override
-        public void setHolder(@NotNull ServerPlayer holder) {
-          items = holder.getInventory().items;
-        }
-      });
+      slots.set(
+          localIndex,
+          new ContentList(owner, invIndex, type) {
+            @Override
+            public void setHolder(@NotNull ServerPlayer holder) {
+              items = holder.getInventory().getNonEquipmentItems();
+            }
+          }
+      );
     }
     return listSize;
   }
 
   private int addArmor(int startIndex) {
-    int listSize = owner.getInventory().armor.size();
-
-    for (int i = 0; i < listSize; ++i) {
-      // Armor slots go bottom to top; boots are slot 0, helmet is slot 3.
-      // Since we have to display horizontally due to space restrictions,
-      // making the left side the "top" is more user-friendly.
-      int armorIndex;
-      EquipmentSlot slot;
-      switch (i) {
-        case 3 -> {
-          armorIndex = 0;
-          slot = EquipmentSlot.FEET;
-        }
-        case 2 -> {
-          armorIndex = 1;
-          slot = EquipmentSlot.LEGS;
-        }
-        case 1 -> {
-          armorIndex = 2;
-          slot = EquipmentSlot.CHEST;
-        }
-        case 0 -> {
-          armorIndex = 3;
-          slot = EquipmentSlot.HEAD;
-        }
-        default -> {
-          // In the event that new armor slots are added, they can be placed at the end.
-          armorIndex = i;
-          slot = EquipmentSlot.MAINHAND;
-        }
+    // Armor slots go bottom to top; boots are first and helmet is last.
+    // Since we have to display horizontally due to space restrictions,
+    // making the left side the "top" is more user-friendly.
+    EquipmentSlot[] sorted = Inventory.EQUIPMENT_SLOT_MAPPING.int2ObjectEntrySet()
+        .stream()
+        .sorted(Comparator.comparingInt(Int2ObjectMap.Entry::getIntKey))
+        .map(Map.Entry::getValue)
+        .toArray(EquipmentSlot[]::new);
+    int localIndex = 0;
+    for (int i = sorted.length - 1; i >= 0; --i) {
+      // Skip off-hand, handled separately. Also skip non-player slots.
+      if (sorted[i].getType() != EquipmentSlot.Type.HUMANOID_ARMOR) {
+        continue;
       }
 
-      slots.set(startIndex + i, new ContentEquipment(owner, armorIndex, slot));
+      slots.set(startIndex + localIndex, new ContentEquipment(owner, sorted[i]));
+      ++localIndex;
     }
 
-    return startIndex + listSize;
+    return startIndex + localIndex;
   }
 
   private int addOffHand(int startIndex) {
-    int listSize = owner.getInventory().offhand.size();
-    for (int localIndex = 0; localIndex < listSize; ++localIndex) {
-      slots.set(startIndex + localIndex, new ContentOffHand(owner, localIndex));
+    // No off-hand?
+    if (!Inventory.EQUIPMENT_SLOT_MAPPING.containsValue(EquipmentSlot.OFFHAND)) {
+      return startIndex;
     }
-    return startIndex + listSize;
+
+    slots.set(startIndex, new ContentOffHand(owner));
+    return startIndex + 1;
   }
 
   private int addCrafting(int startIndex, boolean pretty) {
@@ -182,16 +173,17 @@ public class OpenInventory implements Container, InternalOwned<ServerPlayer>, IS
 
     if (pretty) {
       slots.set(startIndex + 2, new ContentViewOnly(owner) {
-        @Override
-        public Slot asSlot(Container container, int slot, int x, int y) {
-          return new SlotViewOnly(container, slot, x, y) {
             @Override
-            public ItemStack getOrDefault() {
-              return Placeholders.craftingOutput;
+            public Slot asSlot(Container container, int slot, int x, int y) {
+              return new SlotViewOnly(container, slot, x, y) {
+                @Override
+                public ItemStack getOrDefault() {
+                  return Placeholders.craftingOutput;
+                }
+              };
             }
-          };
-        }
-      });
+          }
+      );
       slots.set(startIndex + 11, getCraftingResult(owner));
     }
 
@@ -256,9 +248,6 @@ public class OpenInventory implements Container, InternalOwned<ServerPlayer>, IS
     slots.forEach(slot -> slot.setHolder(newOwner));
   }
 
-  @Override
-  public void setPlayerOffline() {}
-
   @Override
   public boolean isInUse() {
     return !transaction.isEmpty();
@@ -280,22 +269,22 @@ public class OpenInventory implements Container, InternalOwned<ServerPlayer>, IS
   }
 
   @Override
-  public ItemStack getItem(int index) {
+  public @NotNull ItemStack getItem(int index) {
     return slots.get(index).get();
   }
 
   @Override
-  public ItemStack removeItem(int index, int amount) {
+  public @NotNull ItemStack removeItem(int index, int amount) {
     return slots.get(index).removePartial(amount);
   }
 
   @Override
-  public ItemStack removeItemNoUpdate(int index) {
+  public @NotNull ItemStack removeItemNoUpdate(int index) {
     return slots.get(index).remove();
   }
 
   @Override
-  public void setItem(int index, ItemStack itemStack) {
+  public void setItem(int index, @NotNull ItemStack itemStack) {
     slots.get(index).set(itemStack);
   }
 
@@ -310,7 +299,8 @@ public class OpenInventory implements Container, InternalOwned<ServerPlayer>, IS
   }
 
   @Override
-  public void setChanged() {}
+  public void setChanged() {
+  }
 
   @Override
   public boolean stillValid(@NotNull Player player) {
@@ -327,17 +317,17 @@ public class OpenInventory implements Container, InternalOwned<ServerPlayer>, IS
   }
 
   @Override
-  public void onOpen(CraftHumanEntity viewer) {
+  public void onOpen(@NotNull CraftHumanEntity viewer) {
     transaction.add(viewer);
   }
 
   @Override
-  public void onClose(CraftHumanEntity viewer) {
+  public void onClose(@NotNull CraftHumanEntity viewer) {
     transaction.remove(viewer);
   }
 
   @Override
-  public List<HumanEntity> getViewers() {
+  public @NotNull List<HumanEntity> getViewers() {
     return transaction;
   }
 

internal/common/src/main/java/com/lishid/openinv/internal/common/container/bukkit/OpenDummyInventory.java

@@ -109,7 +109,8 @@ public class OpenDummyInventory extends CraftInventory implements ViewOnly {
   @SuppressWarnings("NonApiType")
   @Override
   public @NotNull HashMap<Integer, ItemStack> all(
-      @NotNull Material material) throws IllegalArgumentException {
+      @NotNull Material material
+  ) throws IllegalArgumentException {
     return new HashMap<>();
   }
 

internal/common/src/main/java/com/lishid/openinv/internal/common/container/bukkit/OpenDummyPlayerInventory.java

@@ -22,12 +22,12 @@ public class OpenDummyPlayerInventory extends OpenDummyInventory implements Play
   }
 
   @Override
-  public @NotNull ItemStack[] getArmorContents() {
+  public @NotNull ItemStack @NotNull [] getArmorContents() {
     return new ItemStack[4];
   }
 
   @Override
-  public @NotNull ItemStack[] getExtraContents() {
+  public @NotNull ItemStack @NotNull [] getExtraContents() {
     return new ItemStack[4];
   }
 
@@ -57,17 +57,17 @@ public class OpenDummyPlayerInventory extends OpenDummyInventory implements Play
   }
 
   @Override
-  public @Nullable ItemStack getItem(@NotNull EquipmentSlot slot) {
-    return null;
+  public @NotNull ItemStack getItem(@NotNull EquipmentSlot slot) {
+    return new ItemStack(Material.AIR);
   }
 
   @Override
-  public void setArmorContents(@Nullable ItemStack[] items) {
+  public void setArmorContents(ItemStack @NotNull [] items) {
 
   }
 
   @Override
-  public void setExtraContents(@Nullable ItemStack[] items) {
+  public void setExtraContents(ItemStack @NotNull [] items) {
 
   }
 
@@ -111,6 +111,7 @@ public class OpenDummyPlayerInventory extends OpenDummyInventory implements Play
 
   }
 
+  @SuppressWarnings("InlineMeSuggester")
   @Deprecated
   @Override
   public @NotNull ItemStack getItemInHand() {

internal/common/src/main/java/com/lishid/openinv/internal/common/container/bukkit/OpenPlayerInventory.java

@@ -14,6 +14,8 @@ import org.bukkit.inventory.PlayerInventory;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.List;
+
 public class OpenPlayerInventory extends CraftInventory implements PlayerInventory {
 
   public OpenPlayerInventory(@NotNull OpenInventory inventory) {
@@ -26,7 +28,7 @@ public class OpenPlayerInventory extends CraftInventory implements PlayerInvento
   }
 
   @Override
-  public ItemStack[] getContents() {
+  public ItemStack @NotNull [] getContents() {
     return asCraftMirror(getInventory().getOwnerHandle().getInventory().getContents());
   }
 
@@ -46,13 +48,13 @@ public class OpenPlayerInventory extends CraftInventory implements PlayerInvento
   }
 
   @Override
-  public ItemStack[] getStorageContents() {
-    return asCraftMirror(getInventory().getOwnerHandle().getInventory().items);
+  public ItemStack @NotNull [] getStorageContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().getNonEquipmentItems());
   }
 
   @Override
   public void setStorageContents(ItemStack[] items) throws IllegalArgumentException {
-    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().items;
+    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().getNonEquipmentItems();
     int size = list.size();
     Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
     for (int index = 0; index < items.length; ++index) {
@@ -71,111 +73,115 @@ public class OpenPlayerInventory extends CraftInventory implements PlayerInvento
   }
 
   @Override
-  public @NotNull ItemStack[] getArmorContents() {
-    return asCraftMirror(getInventory().getOwnerHandle().getInventory().armor);
+  public @NotNull ItemStack @NotNull [] getArmorContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().getArmorContents());
   }
 
   @Override
-  public void setArmorContents(@Nullable ItemStack[] items) {
-    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().armor;
-    int size = list.size();
+  public void setArmorContents(ItemStack @NotNull [] items) {
+    int size = Inventory.EQUIPMENT_SLOTS_SORTED_BY_INDEX.length;
     Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
     for (int index = 0; index < items.length; ++index) {
-      list.set(index, CraftItemStack.asNMSCopy(items[index]));
+      getInventory().getOwnerHandle().getInventory().equipment.set(
+          Inventory.EQUIPMENT_SLOTS_SORTED_BY_INDEX[index],
+          CraftItemStack.asNMSCopy(items[index])
+      );
     }
   }
 
   @Override
-  public @NotNull ItemStack[] getExtraContents() {
-    return asCraftMirror(getInventory().getOwnerHandle().getInventory().offhand);
+  public @NotNull ItemStack @NotNull [] getExtraContents() {
+    return asCraftMirror(List.of(getInventory().getOwnerHandle().getInventory().equipment.get(EquipmentSlot.OFFHAND)));
   }
 
   @Override
-  public void setExtraContents(@Nullable ItemStack[] items) {
-    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().offhand;
-    int size = list.size();
-    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
-    for (int index = 0; index < items.length; ++index) {
-      list.set(index, CraftItemStack.asNMSCopy(items[index]));
+  public void setExtraContents(ItemStack @NotNull [] items) {
+    Preconditions.checkArgument(items.length <= 1, "items.length must be <= 1");
+    for (ItemStack item : items) {
+      getInventory().getOwnerHandle().getInventory().equipment.set(EquipmentSlot.OFFHAND, CraftItemStack.asNMSCopy(item));
     }
   }
 
   @Override
-  public @Nullable ItemStack getHelmet() {
-    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
-        .getArmor(EquipmentSlot.HEAD.getIndex()));
+  public @NotNull ItemStack getHelmet() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory().equipment
+        .get(EquipmentSlot.HEAD));
   }
 
   @Override
   public void setHelmet(@Nullable ItemStack helmet) {
-    getInventory().getOwnerHandle().getInventory().armor
-        .set(EquipmentSlot.HEAD.getIndex(), CraftItemStack.asNMSCopy(helmet));
+    getInventory().getOwnerHandle().getInventory().equipment
+        .set(EquipmentSlot.HEAD, CraftItemStack.asNMSCopy(helmet));
   }
 
   @Override
-  public @Nullable ItemStack getChestplate() {
-    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
-        .getArmor(EquipmentSlot.HEAD.getIndex()));
+  public @NotNull ItemStack getChestplate() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory().equipment
+        .get(EquipmentSlot.CHEST));
   }
 
   @Override
   public void setChestplate(@Nullable ItemStack chestplate) {
-    getInventory().getOwnerHandle().getInventory().armor
-        .set(EquipmentSlot.CHEST.getIndex(), CraftItemStack.asNMSCopy(chestplate));
+    getInventory().getOwnerHandle().getInventory().equipment
+        .set(EquipmentSlot.CHEST, CraftItemStack.asNMSCopy(chestplate));
   }
 
   @Override
-  public @Nullable ItemStack getLeggings() {
-    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
-        .getArmor(EquipmentSlot.LEGS.getIndex()));
+  public @NotNull ItemStack getLeggings() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory().equipment
+        .get(EquipmentSlot.LEGS));
   }
 
   @Override
   public void setLeggings(@Nullable ItemStack leggings) {
-    getInventory().getOwnerHandle().getInventory().armor
-        .set(EquipmentSlot.LEGS.getIndex(), CraftItemStack.asNMSCopy(leggings));
+    getInventory().getOwnerHandle().getInventory().equipment
+        .set(EquipmentSlot.LEGS, CraftItemStack.asNMSCopy(leggings));
   }
 
   @Override
-  public @Nullable ItemStack getBoots() {
-    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
-        .getArmor(EquipmentSlot.FEET.getIndex()));
+  public @NotNull ItemStack getBoots() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory().equipment
+        .get(EquipmentSlot.FEET));
   }
 
   @Override
   public void setBoots(@Nullable ItemStack boots) {
-    getInventory().getOwnerHandle().getInventory().armor
-        .set(EquipmentSlot.FEET.getIndex(), CraftItemStack.asNMSCopy(boots));
+    getInventory().getOwnerHandle().getInventory().equipment
+        .set(EquipmentSlot.FEET, CraftItemStack.asNMSCopy(boots));
   }
 
   @Override
   public @NotNull ItemStack getItemInMainHand() {
     Inventory internal = getInventory().getOwnerHandle().getInventory();
-    return CraftItemStack.asCraftMirror(internal.getItem(internal.selected));
+    return CraftItemStack.asCraftMirror(internal.getSelectedItem());
   }
 
   @Override
   public void setItemInMainHand(@Nullable ItemStack item) {
     Inventory internal = getInventory().getOwnerHandle().getInventory();
-    internal.setItem(internal.selected, CraftItemStack.asNMSCopy(item));
+    internal.setSelectedItem(CraftItemStack.asNMSCopy(item));
   }
 
   @Override
   public @NotNull ItemStack getItemInOffHand() {
-    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory().offhand.getFirst());
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory().equipment
+        .get(EquipmentSlot.OFFHAND));
   }
 
   @Override
   public void setItemInOffHand(@Nullable ItemStack item) {
-    getInventory().getOwnerHandle().getInventory().offhand.set(0, CraftItemStack.asNMSCopy(item));
+    getInventory().getOwnerHandle().getInventory().equipment
+        .set(EquipmentSlot.OFFHAND, CraftItemStack.asNMSCopy(item));
   }
 
+  @SuppressWarnings("InlineMeSuggester")
   @Deprecated
   @Override
   public @NotNull ItemStack getItemInHand() {
     return getItemInMainHand();
   }
 
+  @SuppressWarnings("InlineMeSuggester")
   @Deprecated
   @Override
   public void setItemInHand(@Nullable ItemStack stack) {
@@ -185,17 +191,17 @@ public class OpenPlayerInventory extends CraftInventory implements PlayerInvento
   @Override
   public int getHeldItemSlot() {
     Inventory internal = getInventory().getOwnerHandle().getInventory();
-    return internal.items.size() - 9 + internal.selected;
+    return internal.getNonEquipmentItems().size() - 9 + internal.getSelectedSlot();
   }
 
   @Override
   public void setHeldItemSlot(int slot) {
     slot %= 9;
-    getInventory().getOwnerHandle().getInventory().selected = slot;
+    getInventory().getOwnerHandle().getInventory().setSelectedSlot(slot);
   }
 
   @Override
-  public @Nullable ItemStack getItem(@NotNull org.bukkit.inventory.EquipmentSlot slot) {
+  public @NotNull ItemStack getItem(@NotNull org.bukkit.inventory.EquipmentSlot slot) {
     return switch (slot) {
       case HAND -> getItemInMainHand();
       case OFF_HAND -> getItemInOffHand();

internal/common/src/main/java/com/lishid/openinv/internal/common/container/menu/OpenChestMenu.java

@@ -8,6 +8,7 @@ import com.lishid.openinv.internal.common.container.slot.SlotPlaceholder;
 import com.lishid.openinv.internal.common.container.slot.SlotViewOnly;
 import it.unimi.dsi.fastutil.ints.IntArrayList;
 import it.unimi.dsi.fastutil.ints.IntList;
+import net.minecraft.network.HashedStack;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.Container;
 import net.minecraft.world.entity.player.Player;
@@ -19,6 +20,7 @@ import net.minecraft.world.inventory.ContainerListener;
 import net.minecraft.world.inventory.ContainerSynchronizer;
 import net.minecraft.world.inventory.DataSlot;
 import net.minecraft.world.inventory.MenuType;
+import net.minecraft.world.inventory.RemoteSlot;
 import net.minecraft.world.inventory.Slot;
 import net.minecraft.world.item.ItemStack;
 import org.bukkit.craftbukkit.inventory.CraftInventoryView;
@@ -35,6 +37,7 @@ import java.util.function.Supplier;
 /**
  * An extension of {@link AbstractContainerMenu} that supports {@link SlotPlaceholder placeholders}.
  */
+@SuppressWarnings("HidingField") // Revisit when removing 1.21.4 support
 public abstract class OpenChestMenu<T extends Container & ISpecialInventory & InternalOwned<ServerPlayer>>
     extends AbstractContainerMenu {
 
@@ -47,19 +50,20 @@ public abstract class OpenChestMenu<T extends Container & ISpecialInventory & In
   protected final int topSize;
   private CraftInventoryView<OpenChestMenu<T>, Inventory> bukkitEntity;
   // Syncher fields
-  private @Nullable ContainerSynchronizer synchronizer;
-  private final List<DataSlot> dataSlots = new ArrayList<>();
-  private final IntList remoteDataSlots = new IntArrayList();
-  private final List<ContainerListener> containerListeners = new ArrayList<>();
-  private ItemStack remoteCarried = ItemStack.EMPTY;
-  private boolean suppressRemoteUpdates;
+  protected @Nullable ContainerSynchronizer synchronizer;
+  protected final List<DataSlot> dataSlots = new ArrayList<>();
+  protected final IntList remoteDataSlots = new IntArrayList();
+  protected final List<ContainerListener> containerListeners = new ArrayList<>();
+  private RemoteSlot remoteCarried = RemoteSlot.PLACEHOLDER;
+  protected boolean suppressRemoteUpdates;
 
   protected OpenChestMenu(
       @NotNull MenuType<ChestMenu> type,
       int containerCounter,
       @NotNull T container,
       @NotNull ServerPlayer viewer,
-      boolean viewOnly) {
+      boolean viewOnly
+  ) {
     super(type, containerCounter);
     this.container = container;
     this.viewer = viewer;
@@ -121,7 +125,8 @@ public abstract class OpenChestMenu<T extends Container & ISpecialInventory & In
     };
   }
 
-  protected void preSlotSetup() {}
+  protected void preSlotSetup() {
+  }
 
   protected @NotNull Slot getUpperSlot(int index, int x, int y) {
     Slot slot = new Slot(container, index, x, y);
@@ -304,7 +309,7 @@ public abstract class OpenChestMenu<T extends Container & ISpecialInventory & In
     slot.index = this.slots.size();
     this.slots.add(slot);
     this.lastSlots.add(ItemStack.EMPTY);
-    this.remoteSlots.add(ItemStack.EMPTY);
+    this.remoteSlots.add(this.synchronizer != null ? this.synchronizer.createSlot() : RemoteSlot.PLACEHOLDER);
     return slot;
   }
 
@@ -333,32 +338,38 @@ public abstract class OpenChestMenu<T extends Container & ISpecialInventory & In
   @Override
   public void setSynchronizer(@NotNull ContainerSynchronizer containerSynchronizer) {
     this.synchronizer = containerSynchronizer;
+    this.remoteCarried = synchronizer.createSlot();
+    this.remoteSlots.replaceAll(slot -> synchronizer.createSlot());
     this.sendAllDataToRemote();
   }
 
   @Override
   public void sendAllDataToRemote() {
+    List<ItemStack> contentsCopy = new ArrayList<>();
     for (int index = 0; index < slots.size(); ++index) {
       Slot slot = slots.get(index);
-      this.remoteSlots.set(index, (slot instanceof SlotPlaceholder placeholder ? placeholder.getOrDefault() : slot.getItem()).copy());
+      ItemStack itemStack = slot instanceof SlotPlaceholder placeholder ? placeholder.getOrDefault() : slot.getItem();
+      contentsCopy.add(itemStack);
+      this.remoteSlots.get(index).force(itemStack);
     }
 
-    remoteCarried = getCarried().copy();
+    remoteCarried.force(getCarried());
 
     for (int index = 0; index < this.dataSlots.size(); ++index) {
       this.remoteDataSlots.set(index, this.dataSlots.get(index).get());
     }
 
     if (this.synchronizer != null) {
-      this.synchronizer.sendInitialData(this, this.remoteSlots, this.remoteCarried, this.remoteDataSlots.toIntArray());
+      this.synchronizer.sendInitialData(this, contentsCopy, this.getCarried().copy(), this.remoteDataSlots.toIntArray());
     }
   }
 
   @Override
   public void broadcastCarriedItem() {
-    this.remoteCarried = this.getCarried().copy();
+    ItemStack carried = this.getCarried();
+    this.remoteCarried.force(carried);
     if (this.synchronizer != null) {
-      this.synchronizer.sendCarriedChange(this, this.remoteCarried);
+      this.synchronizer.sendCarriedChange(this, carried.copy());
     }
   }
 
@@ -427,12 +438,11 @@ public abstract class OpenChestMenu<T extends Container & ISpecialInventory & In
 
   private void synchronizeSlotToRemote(int i, ItemStack itemStack, Supplier<ItemStack> supplier) {
     if (!this.suppressRemoteUpdates) {
-      ItemStack itemStack1 = this.remoteSlots.get(i);
-      if (!ItemStack.matches(itemStack1, itemStack)) {
-        ItemStack itemstack2 = supplier.get();
-        this.remoteSlots.set(i, itemstack2);
+      RemoteSlot slot = this.remoteSlots.get(i);
+      if (!slot.matches(itemStack)) {
+        slot.force(itemStack);
         if (this.synchronizer != null) {
-          this.synchronizer.sendSlotChange(this, i, itemstack2);
+          this.synchronizer.sendSlotChange(this, i, supplier.get());
         }
       }
     }
@@ -451,17 +461,20 @@ public abstract class OpenChestMenu<T extends Container & ISpecialInventory & In
   }
 
   private void synchronizeCarriedToRemote() {
-    if (!this.suppressRemoteUpdates && !ItemStack.matches(this.getCarried(), this.remoteCarried)) {
-      this.remoteCarried = this.getCarried().copy();
-      if (this.synchronizer != null) {
-        this.synchronizer.sendCarriedChange(this, this.remoteCarried);
+    if (!this.suppressRemoteUpdates) {
+      ItemStack carried = this.getCarried();
+      if (!this.remoteCarried.matches(carried)) {
+        this.remoteCarried.force(carried);
+        if (this.synchronizer != null) {
+          this.synchronizer.sendCarriedChange(this, carried.copy());
+        }
       }
     }
   }
 
   @Override
-  public void setRemoteCarried(ItemStack itemstack) {
-    this.remoteCarried = itemstack.copy();
+  public void setRemoteCarried(@NotNull HashedStack stack) {
+    this.remoteCarried.receive(stack);
   }
 
   @Override

internal/common/src/main/java/com/lishid/openinv/internal/common/container/menu/OpenEnderChestMenu.java

@@ -13,7 +13,8 @@ public class OpenEnderChestMenu extends OpenChestMenu<OpenEnderChest> {
       @NotNull OpenEnderChest enderChest,
       @NotNull ServerPlayer viewer,
       int containerId,
-      boolean viewOnly) {
+      boolean viewOnly
+  ) {
     super(getChestMenuType(enderChest.getContainerSize()), containerId, enderChest, viewer, viewOnly);
   }
 

internal/common/src/main/java/com/lishid/openinv/internal/common/container/menu/OpenInventoryMenu.java

@@ -35,7 +35,7 @@ public class OpenInventoryMenu extends OpenChestMenu<OpenInventory> {
     int size = inventory.getContainerSize();
     // Disallow duplicate access to own main inventory contents.
     if (inventory.getOwnerHandle().equals(viewer)) {
-      size -= viewer.getInventory().items.size();
+      size -= viewer.getInventory().getNonEquipmentItems().size();
       size = ((int) Math.ceil(size / 9.0)) * 9;
     }
 
@@ -44,7 +44,7 @@ public class OpenInventoryMenu extends OpenChestMenu<OpenInventory> {
 
   @Override
   protected void preSlotSetup() {
-    offset = ownContainer ? viewer.getInventory().items.size() : 0;
+    offset = ownContainer ? viewer.getInventory().getNonEquipmentItems().size() : 0;
   }
 
   @Override
@@ -133,8 +133,11 @@ public class OpenInventoryMenu extends OpenChestMenu<OpenInventory> {
         if (rawSlot == InventoryView.OUTSIDE || rawSlot == -1) {
           return null;
         }
-        Preconditions.checkArgument(rawSlot >= 0 && rawSlot < topSize + offset + BOTTOM_INVENTORY_SIZE,
-            "Slot %s outside of inventory", rawSlot);
+        Preconditions.checkArgument(
+            rawSlot >= 0 && rawSlot < topSize + offset + BOTTOM_INVENTORY_SIZE,
+            "Slot %s outside of inventory",
+            rawSlot
+        );
         if (rawSlot > topSize) {
           return getBottomInventory();
         }
@@ -221,7 +224,7 @@ public class OpenInventoryMenu extends OpenChestMenu<OpenInventory> {
         // If this is gear, try to move it to the correct slot first.
         case OFFHAND, FEET, LEGS, CHEST, HEAD -> {
           // Locate the correct slot in the contents following the main inventory.
-          for (int extra = container.getOwnerHandle().getInventory().items.size() - offset; extra < topSize; ++extra) {
+          for (int extra = container.getOwnerHandle().getInventory().getNonEquipmentItems().size() - offset; extra < topSize; ++extra) {
             Slot extraSlot = getSlot(extra);
             if (extraSlot instanceof ContentEquipment.SlotEquipment equipSlot
                 && equipSlot.getEquipmentSlot() == equipmentSlot) {
@@ -244,7 +247,7 @@ public class OpenInventoryMenu extends OpenChestMenu<OpenInventory> {
         }
       } else {
         // If we didn't move to a gear slot, try to move to a main inventory slot.
-        if (!movedGear && !this.moveItemStackTo(itemStack, 0, container.getOwnerHandle().getInventory().items.size(), true)) {
+        if (!movedGear && !this.moveItemStackTo(itemStack, 0, container.getOwnerHandle().getInventory().getNonEquipmentItems().size(), true)) {
           return ItemStack.EMPTY;
         }
       }

internal/common/src/main/java/com/lishid/openinv/internal/common/container/slot/ContentCrafting.java

@@ -1,7 +1,7 @@
 package com.lishid.openinv.internal.common.container.slot;
 
 import com.lishid.openinv.internal.common.container.slot.placeholder.Placeholders;
-import com.lishid.openinv.internal.common.player.OpenPlayer;
+import com.lishid.openinv.internal.common.player.BaseOpenPlayer;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.Container;
 import net.minecraft.world.ContainerHelper;
@@ -35,7 +35,7 @@ public class ContentCrafting implements Content {
     // Player must be online and not in creative - since the creative client is (semi-)authoritative,
     // it ignores changes without extra help, and will delete the item as a result.
     // Spectator mode is technically possible but may cause the item to be dropped if the client opens an inventory.
-    return OpenPlayer.isConnected(holder.connection) && holder.gameMode.isSurvival();
+    return BaseOpenPlayer.isConnected(holder.connection) && holder.gameMode.isSurvival();
   }
 
   @Override

internal/common/src/main/java/com/lishid/openinv/internal/common/container/slot/ContentCursor.java

@@ -1,7 +1,7 @@
 package com.lishid.openinv.internal.common.container.slot;
 
 import com.lishid.openinv.internal.common.container.slot.placeholder.Placeholders;
-import com.lishid.openinv.internal.common.player.OpenPlayer;
+import com.lishid.openinv.internal.common.player.BaseOpenPlayer;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.Container;
 import net.minecraft.world.entity.player.Player;
@@ -64,7 +64,7 @@ public class ContentCursor implements Content {
     // Player must be online and not in creative - since the creative client is (semi-)authoritative,
     // it ignores changes without extra help, and will delete the item as a result.
     // Spectator mode is technically possible but may cause the item to be dropped if the client opens an inventory.
-    return OpenPlayer.isConnected(holder.connection) && holder.gameMode.isSurvival();
+    return BaseOpenPlayer.isConnected(holder.connection) && holder.gameMode.isSurvival();
   }
 
   @Override

internal/common/src/main/java/com/lishid/openinv/internal/common/container/slot/ContentDrop.java

@@ -1,7 +1,7 @@
 package com.lishid.openinv.internal.common.container.slot;
 
 import com.lishid.openinv.internal.common.container.slot.placeholder.Placeholders;
-import com.lishid.openinv.internal.common.player.OpenPlayer;
+import com.lishid.openinv.internal.common.player.BaseOpenPlayer;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.Container;
 import net.minecraft.world.inventory.Slot;
@@ -64,14 +64,14 @@ public class ContentDrop implements Content {
 
     @Override
     public ItemStack getOrDefault() {
-      return OpenPlayer.isConnected(holder.connection)
+      return BaseOpenPlayer.isConnected(holder.connection)
           ? Placeholders.drop
           : Placeholders.blockedOffline;
     }
 
     @Override
     public boolean mayPlace(@NotNull ItemStack itemStack) {
-      return OpenPlayer.isConnected(holder.connection);
+      return BaseOpenPlayer.isConnected(holder.connection);
     }
 
     @Override

internal/common/src/main/java/com/lishid/openinv/internal/common/container/slot/ContentEquipment.java

@@ -3,6 +3,7 @@ package com.lishid.openinv.internal.common.container.slot;
 import com.lishid.openinv.internal.common.container.slot.placeholder.Placeholders;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.Container;
+import net.minecraft.world.entity.EntityEquipment;
 import net.minecraft.world.entity.EquipmentSlot;
 import net.minecraft.world.inventory.Slot;
 import net.minecraft.world.item.ItemStack;
@@ -12,13 +13,14 @@ import org.jetbrains.annotations.NotNull;
 /**
  * A slot for equipment that displays placeholders if empty.
  */
-public class ContentEquipment extends ContentList {
+public class ContentEquipment implements Content {
 
+  private EntityEquipment equipment;
   private final ItemStack placeholder;
   private final EquipmentSlot equipmentSlot;
 
-  public ContentEquipment(ServerPlayer holder, int index, EquipmentSlot equipmentSlot) {
-    super(holder, index, InventoryType.SlotType.ARMOR);
+  public ContentEquipment(ServerPlayer holder, EquipmentSlot equipmentSlot) {
+    setHolder(holder);
     placeholder = switch (equipmentSlot) {
       case HEAD -> Placeholders.emptyHelmet;
       case CHEST -> Placeholders.emptyChestplate;
@@ -31,7 +33,31 @@ public class ContentEquipment extends ContentList {
 
   @Override
   public void setHolder(@NotNull ServerPlayer holder) {
-    this.items = holder.getInventory().armor;
+    this.equipment = holder.getInventory().equipment;
+  }
+
+  @Override
+  public ItemStack get() {
+    return equipment.get(equipmentSlot);
+  }
+
+  @Override
+  public ItemStack remove() {
+    return equipment.set(equipmentSlot, ItemStack.EMPTY);
+  }
+
+  @Override
+  public ItemStack removePartial(int amount) {
+    ItemStack current = get();
+    if (!current.isEmpty() && amount > 0) {
+      return current.split(amount);
+    }
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public void set(ItemStack itemStack) {
+    equipment.set(equipmentSlot, itemStack);
   }
 
   @Override
@@ -39,6 +65,11 @@ public class ContentEquipment extends ContentList {
     return new SlotEquipment(container, slot, x, y);
   }
 
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return InventoryType.SlotType.ARMOR;
+  }
+
   public class SlotEquipment extends SlotPlaceholder {
 
     private ServerPlayer viewer;

internal/common/src/main/java/com/lishid/openinv/internal/common/container/slot/ContentOffHand.java

@@ -1,6 +1,6 @@
 package com.lishid.openinv.internal.common.container.slot;
 
-import com.lishid.openinv.internal.common.player.OpenPlayer;
+import com.lishid.openinv.internal.common.player.BaseOpenPlayer;
 import net.minecraft.network.protocol.game.ClientboundContainerSetSlotPacket;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.Container;
@@ -17,13 +17,13 @@ public class ContentOffHand extends ContentEquipment {
 
   private ServerPlayer holder;
 
-  public ContentOffHand(ServerPlayer holder, int localIndex) {
-    super(holder, localIndex, EquipmentSlot.OFFHAND);
+  public ContentOffHand(ServerPlayer holder) {
+    super(holder, EquipmentSlot.OFFHAND);
   }
 
   @Override
   public void setHolder(@NotNull ServerPlayer holder) {
-    this.items = holder.getInventory().offhand;
+    super.setHolder(holder);
     this.holder = holder;
   }
 
@@ -37,13 +37,14 @@ public class ContentOffHand extends ContentEquipment {
     return new SlotEquipment(container, slot, x, y) {
       @Override
       public void setChanged() {
-        if (OpenPlayer.isConnected(holder.connection) && holder.containerMenu != holder.inventoryMenu) {
+        if (BaseOpenPlayer.isConnected(holder.connection) && holder.containerMenu != holder.inventoryMenu) {
           holder.connection.send(
               new ClientboundContainerSetSlotPacket(
                   holder.inventoryMenu.containerId,
                   holder.inventoryMenu.incrementStateId(),
                   InventoryMenu.SHIELD_SLOT,
-                  holder.getOffhandItem()));
+                  holder.getOffhandItem()
+              ));
         }
       }
     };

internal/common/src/main/java/com/lishid/openinv/internal/common/container/slot/placeholder/PlaceholderLoader.java

@@ -1,18 +1,40 @@
 package com.lishid.openinv.internal.common.container.slot.placeholder;
 
 import net.minecraft.core.component.DataComponents;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.TagParser;
 import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.item.component.CustomModelData;
+import net.minecraft.world.item.component.DyedItemColor;
+import net.minecraft.world.item.component.TooltipDisplay;
+import org.jetbrains.annotations.NotNull;
 
+import java.util.LinkedHashSet;
 import java.util.List;
 
 public class PlaceholderLoader extends PlaceholderLoaderBase {
 
   private static final CustomModelData DEFAULT_CUSTOM_MODEL_DATA = new CustomModelData(List.of(), List.of(), List.of("openinv:custom"), List.of());
+  private static final TooltipDisplay HIDE_TOOLTIP = new TooltipDisplay(true, new LinkedHashSet<>());
 
   @Override
-  protected void addModelData(ItemStack itemStack) {
+  protected @NotNull CompoundTag parseTag(@NotNull String itemText) throws Exception {
+    return TagParser.parseCompoundFully(itemText);
+  }
+
+  @Override
+  protected void addModelData(@NotNull ItemStack itemStack) {
     itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
   }
 
+  @Override
+  protected void hideTooltip(@NotNull ItemStack itemStack) {
+    itemStack.set(DataComponents.TOOLTIP_DISPLAY, HIDE_TOOLTIP);
+  }
+
+  @Override
+  protected DyedItemColor getDye(int rgb) {
+    return new DyedItemColor(rgb);
+  }
+
 }

internal/common/src/main/java/com/lishid/openinv/internal/common/container/slot/placeholder/PlaceholderLoaderBase.java

@@ -1,13 +1,13 @@
 package com.lishid.openinv.internal.common.container.slot.placeholder;
 
+import com.mojang.serialization.DataResult;
 import net.minecraft.core.Registry;
 import net.minecraft.core.RegistryAccess;
 import net.minecraft.core.component.DataComponents;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.nbt.CompoundTag;
-import net.minecraft.nbt.TagParser;
+import net.minecraft.nbt.NbtOps;
 import net.minecraft.network.chat.Component;
-import net.minecraft.util.Unit;
 import net.minecraft.world.item.DyeColor;
 import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.item.Items;
@@ -23,50 +23,40 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.util.List;
-import java.util.Optional;
 
 public abstract class PlaceholderLoaderBase {
 
-  protected PlaceholderLoaderBase() {
+  public void load(@Nullable ConfigurationSection section) throws Exception {
+    Placeholders.craftingOutput = parse(section, "crafting-output", defaultCraftingOutput());
+    Placeholders.cursor = parse(section, "cursor", defaultCursor());
+    Placeholders.drop = parse(section, "drop", defaultDrop());
+    Placeholders.emptyHelmet = parse(section, "empty-helmet", getEmptyArmor(Items.LEATHER_HELMET));
+    Placeholders.emptyChestplate = parse(section, "empty-chestplate", getEmptyArmor(Items.LEATHER_CHESTPLATE));
+    Placeholders.emptyLeggings = parse(section, "empty-leggings", getEmptyArmor(Items.LEATHER_LEGGINGS));
+    Placeholders.emptyBoots = parse(section, "empty-boots", getEmptyArmor(Items.LEATHER_BOOTS));
+    Placeholders.emptyOffHand = parse(section, "empty-off-hand", defaultShield());
+    Placeholders.notSlot = parse(section, "not-a-slot", defaultNotSlot());
+    Placeholders.blockedOffline = parse(section, "blocked.offline", defaultBlockedOffline());
+
     for (GameType type : GameType.values()) {
       // Barrier: "Not available - Creative" etc.
       ItemStack typeItem = new ItemStack(Items.BARRIER);
       typeItem.set(
           DataComponents.ITEM_NAME,
-          Component.translatable("options.narrator.notavailable").append(" - ").append(type.getShortDisplayName()));
+          Component.translatable("options.narrator.notavailable").append(" - ").append(type.getShortDisplayName())
+      );
       Placeholders.BLOCKED_GAME_TYPE.put(type, typeItem);
     }
-    Placeholders.craftingOutput = defaultCraftingOutput();
-    Placeholders.cursor = defaultCursor();
-    Placeholders.drop = defaultDrop();
-    Placeholders.emptyHelmet = getEmptyArmor(Items.LEATHER_HELMET);
-    Placeholders.emptyChestplate = getEmptyArmor(Items.LEATHER_CHESTPLATE);
-    Placeholders.emptyLeggings = getEmptyArmor(Items.LEATHER_LEGGINGS);
-    Placeholders.emptyBoots = getEmptyArmor(Items.LEATHER_BOOTS);
-    Placeholders.emptyOffHand = defaultShield();
-    Placeholders.notSlot = defaultNotSlot();
-    Placeholders.blockedOffline = defaultBlockedOffline();
-  }
 
-  public void load(@Nullable ConfigurationSection section) throws Exception {
-    Placeholders.craftingOutput = parse(section, "crafting-output", Placeholders.craftingOutput);
-    Placeholders.cursor = parse(section, "cursor", Placeholders.cursor);
-    Placeholders.drop = parse(section, "drop", Placeholders.drop);
-    Placeholders.emptyHelmet = parse(section, "empty-helmet", Placeholders.emptyHelmet);
-    Placeholders.emptyChestplate = parse(section, "empty-chestplate", Placeholders.emptyChestplate);
-    Placeholders.emptyLeggings = parse(section, "empty-leggings", Placeholders.emptyLeggings);
-    Placeholders.emptyBoots = parse(section, "empty-boots", Placeholders.emptyBoots);
-    Placeholders.emptyOffHand = parse(section, "empty-off-hand", Placeholders.emptyOffHand);
-    Placeholders.notSlot = parse(section, "not-a-slot", Placeholders.notSlot);
-    Placeholders.blockedOffline = parse(section, "blocked.offline", Placeholders.blockedOffline);
     Placeholders.BLOCKED_GAME_TYPE.put(GameType.CREATIVE, parse(section, "blocked.creative", Placeholders.BLOCKED_GAME_TYPE.get(GameType.CREATIVE)));
     Placeholders.BLOCKED_GAME_TYPE.put(GameType.SPECTATOR, parse(section, "blocked.spectator", Placeholders.BLOCKED_GAME_TYPE.get(GameType.SPECTATOR)));
   }
 
-  private static @NotNull ItemStack parse(
+  protected @NotNull ItemStack parse(
       @Nullable ConfigurationSection section,
       @NotNull String path,
-      @NotNull ItemStack defaultStack) throws Exception {
+      @NotNull ItemStack defaultStack
+  ) throws Exception {
     if (section == null) {
       return defaultStack;
     }
@@ -77,12 +67,24 @@ public abstract class PlaceholderLoaderBase {
       return defaultStack;
     }
 
-    CompoundTag compoundTag = TagParser.parseTag(itemText);
-    Optional<ItemStack> parsed = ItemStack.parse(CraftRegistry.getMinecraftRegistry(), compoundTag);
-    return parsed.filter(itemStack -> !itemStack.isEmpty()).orElse(defaultStack);
+    CompoundTag compoundTag = parseTag(itemText);
+    DataResult<ItemStack> parsed = ItemStack.CODEC.parse(CraftRegistry.getMinecraftRegistry().createSerializationContext(NbtOps.INSTANCE), compoundTag);
+    ItemStack itemStack;
+    try {
+      itemStack = parsed.getOrThrow();
+    } catch (Exception e) {
+      itemStack = null;
+    }
+    return itemStack == null ? defaultStack : itemStack;
   }
 
-  protected abstract void addModelData(ItemStack itemStack);
+  protected abstract @NotNull CompoundTag parseTag(@NotNull String itemText) throws Exception;
+
+  protected abstract void addModelData(@NotNull ItemStack itemStack);
+
+  protected abstract void hideTooltip(@NotNull ItemStack itemStack);
+
+  protected abstract DyedItemColor getDye(int rgb);
 
   protected @NotNull ItemStack defaultCraftingOutput() {
     // Crafting table: "Crafting"
@@ -104,9 +106,11 @@ public abstract class PlaceholderLoaderBase {
         new BannerPatternLayers(List.of(
             new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(halfDiagBottomRight), DyeColor.GRAY),
             new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(downRight), DyeColor.WHITE),
-            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(border), DyeColor.GRAY))));
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(border), DyeColor.GRAY)
+        ))
+    );
     addModelData(itemStack);
-    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+    hideTooltip(itemStack);
     return itemStack;
   }
 
@@ -122,9 +126,9 @@ public abstract class PlaceholderLoaderBase {
   protected @NotNull ItemStack getEmptyArmor(@NotNull ItemLike item) {
     // Inventory-background-grey-ish leather armor with no tooltip
     ItemStack itemStack = new ItemStack(item);
-    DyedItemColor color = new DyedItemColor(0xC8C8C8, false);
+    DyedItemColor color = getDye(0xC8C8C8);
     itemStack.set(DataComponents.DYED_COLOR, color);
-    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+    hideTooltip(itemStack);
     addModelData(itemStack);
     return itemStack;
   }
@@ -146,8 +150,10 @@ public abstract class PlaceholderLoaderBase {
             new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(topLeft), DyeColor.MAGENTA),
             new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(bottomLeft), DyeColor.MAGENTA),
             new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(topRight), DyeColor.BLACK),
-            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(bottomRight), DyeColor.BLACK))));
-    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(bottomRight), DyeColor.BLACK)
+        ))
+    );
+    hideTooltip(itemStack);
     addModelData(itemStack);
     return itemStack;
   }
@@ -155,7 +161,7 @@ public abstract class PlaceholderLoaderBase {
   protected @NotNull ItemStack defaultNotSlot() {
     // White pane with no tooltip
     ItemStack itemStack = new ItemStack(Items.WHITE_STAINED_GLASS_PANE);
-    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+    hideTooltip(itemStack);
     addModelData(itemStack);
     return itemStack;
   }
@@ -166,7 +172,8 @@ public abstract class PlaceholderLoaderBase {
     itemStack.set(DataComponents.ITEM_NAME,
         Component.translatable("options.narrator.notavailable")
             .append(Component.literal(" - "))
-            .append(Component.translatable("gui.socialInteractions.status_offline")));
+            .append(Component.translatable("gui.socialInteractions.status_offline"))
+    );
     return itemStack;
   }
 

internal/common/src/main/java/com/lishid/openinv/internal/common/container/slot/placeholder/Placeholders.java

@@ -1,6 +1,6 @@
 package com.lishid.openinv.internal.common.container.slot.placeholder;
 
-import com.lishid.openinv.internal.common.player.OpenPlayer;
+import com.lishid.openinv.internal.common.player.BaseOpenPlayer;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.level.GameType;
@@ -23,7 +23,7 @@ public final class Placeholders {
   public static @NotNull ItemStack blockedOffline = ItemStack.EMPTY;
 
   public static ItemStack survivalOnly(@NotNull ServerPlayer serverPlayer) {
-    if (!OpenPlayer.isConnected(serverPlayer.connection)) {
+    if (!BaseOpenPlayer.isConnected(serverPlayer.connection)) {
       return blockedOffline;
     }
 

internal/common/src/main/java/com/lishid/openinv/internal/common/player/BaseOpenPlayer.java

@@ -0,0 +1,165 @@
+package com.lishid.openinv.internal.common.player;
+
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NumericTag;
+import net.minecraft.nbt.Tag;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.server.network.ServerGamePacketListenerImpl;
+import net.minecraft.world.level.storage.ValueOutput;
+import org.bukkit.craftbukkit.CraftServer;
+import org.bukkit.craftbukkit.entity.CraftPlayer;
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;
+
+import java.util.Set;
+
+public abstract class BaseOpenPlayer extends CraftPlayer {
+
+  /**
+   * List of tags to always reset when saving.
+   *
+   * @see net.minecraft.world.entity.Entity#saveWithoutId(ValueOutput)
+   * @see net.minecraft.server.level.ServerPlayer#addAdditionalSaveData(ValueOutput)
+   * @see net.minecraft.world.entity.player.Player#addAdditionalSaveData(ValueOutput)
+   * @see net.minecraft.world.entity.LivingEntity#addAdditionalSaveData(ValueOutput)
+   */
+  @Unmodifiable
+  protected static final Set<String> RESET_TAGS = Set.of(
+      // Entity#saveWithoutId(CompoundTag)
+      "CustomName",
+      "CustomNameVisible",
+      "Silent",
+      "NoGravity",
+      "Glowing",
+      "TicksFrozen",
+      "HasVisualFire",
+      "Tags",
+      "Passengers",
+      // ServerPlayer#addAdditionalSaveData(CompoundTag)
+      // Intentional omissions to prevent mount loss: Attach, Entity, and RootVehicle
+      "warden_spawn_tracker",
+      "entered_nether_pos", // Replaces enteredNetherPosition
+      "enteredNetherPosition",
+      "respawn", // Replaces SpawnXyz fields as of 1.21.6
+      "SpawnX",
+      "SpawnY",
+      "SpawnZ",
+      "SpawnForced",
+      "SpawnAngle",
+      "SpawnDimension",
+      "raid_omen_position",
+      "ender_pearls",
+      // Player#addAdditionalSaveData(CompoundTag)
+      "ShoulderEntityLeft",
+      "ShoulderEntityRight",
+      "LastDeathLocation",
+      "current_explosion_impact_pos",
+      // LivingEntity#addAdditionalSaveData(CompoundTag)
+      "active_effects",
+      "sleeping_pos", // Replaces SleepingXyz fields as of 1.21.6
+      "SleepingX",
+      "SleepingY",
+      "SleepingZ",
+      "Brain",
+      "last_hurt_by_player",
+      "last_hurt_by_player_memory_time",
+      "last_hurt_by_mob",
+      "ticks_since_last_hurt_by_mob",
+      "equipment",
+      "locator_bar_icon"
+  );
+
+  private final PlayerManager manager;
+
+  protected BaseOpenPlayer(CraftServer server, ServerPlayer entity, PlayerManager manager) {
+    super(server, entity);
+    this.manager = manager;
+  }
+
+  @Override
+  public void loadData() {
+    manager.loadData(server.getServer(), getHandle());
+  }
+
+  @Override
+  public abstract void saveData();
+
+  @Contract("null -> new")
+  protected @NotNull CompoundTag getWritableTag(@Nullable CompoundTag oldData) {
+    if (oldData == null) {
+      return new CompoundTag();
+    }
+
+    // Copy old data. This is a deep clone, so operating on it should be safe.
+    oldData = oldData.copy();
+
+    // Remove vanilla/server data that is not written every time.
+    oldData.keySet().removeIf(
+        key -> RESET_TAGS.contains(key)
+            || key.startsWith("Bukkit")
+            || (key.startsWith("Paper") && key.length() > 5)
+    );
+
+    return oldData;
+  }
+
+  protected void revertSpecialValues(@NotNull CompoundTag newData, @NotNull CompoundTag oldData) {
+    // Revert automatic updates to play timestamps.
+    copyValue(oldData, newData, "bukkit", "lastPlayed", NumericTag.class);
+    copyValue(oldData, newData, "Paper", "LastSeen", NumericTag.class);
+    copyValue(oldData, newData, "Paper", "LastLogin", NumericTag.class);
+  }
+
+  private <T extends Tag> void copyValue(
+      @NotNull CompoundTag source,
+      @NotNull CompoundTag target,
+      @NotNull String container,
+      @NotNull String key,
+      @SuppressWarnings("SameParameterValue") @NotNull Class<T> tagType
+  ) {
+    CompoundTag oldContainer = getTag(source, container, CompoundTag.class);
+    CompoundTag newContainer = getTag(target, container, CompoundTag.class);
+
+    // New container being null means the server implementation doesn't store this data.
+    if (newContainer == null) {
+      return;
+    }
+
+    // If old tag exists, copy it to new location, removing otherwise.
+    setTag(newContainer, key, getTag(oldContainer, key, tagType));
+  }
+
+  private <T extends Tag> @Nullable T getTag(
+      @Nullable CompoundTag container,
+      @NotNull String key,
+      @NotNull Class<T> dataType
+  ) {
+    if (container == null) {
+      return null;
+    }
+    Tag value = container.get(key);
+    if (value == null || !dataType.isAssignableFrom(value.getClass())) {
+      return null;
+    }
+    return dataType.cast(value);
+  }
+
+  private <T extends Tag> void setTag(
+      @NotNull CompoundTag container,
+      @NotNull String key,
+      @Nullable T data
+  ) {
+    if (data == null) {
+      container.remove(key);
+    } else {
+      container.put(key, data);
+    }
+  }
+
+  public static boolean isConnected(@Nullable ServerGamePacketListenerImpl connection) {
+    return connection != null && !connection.isDisconnected();
+  }
+
+}

internal/common/src/main/java/com/lishid/openinv/internal/common/player/OpenPlayer.java

@@ -5,77 +5,25 @@ import com.mojang.logging.LogUtils;
 import net.minecraft.Util;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.nbt.NbtIo;
-import net.minecraft.nbt.NumericTag;
-import net.minecraft.nbt.Tag;
 import net.minecraft.server.level.ServerPlayer;
-import net.minecraft.server.network.ServerGamePacketListenerImpl;
+import net.minecraft.util.ProblemReporter;
 import net.minecraft.world.level.storage.PlayerDataStorage;
+import net.minecraft.world.level.storage.TagValueOutput;
+import net.minecraft.world.level.storage.ValueOutput;
 import org.bukkit.craftbukkit.CraftServer;
-import org.bukkit.craftbukkit.entity.CraftPlayer;
-import org.jetbrains.annotations.Contract;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
+import org.slf4j.Logger;
 
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.Set;
 
-public class OpenPlayer extends CraftPlayer {
+public class OpenPlayer extends BaseOpenPlayer {
 
-  /**
-   * List of tags to always reset when saving.
-   *
-   * @see net.minecraft.world.entity.Entity#saveWithoutId(CompoundTag)
-   * @see net.minecraft.server.level.ServerPlayer#addAdditionalSaveData(CompoundTag)
-   * @see net.minecraft.world.entity.player.Player#addAdditionalSaveData(CompoundTag)
-   * @see net.minecraft.world.entity.LivingEntity#addAdditionalSaveData(CompoundTag)
-   */
-  private static final Set<String> RESET_TAGS = Set.of(
-      // Entity#saveWithoutId(CompoundTag)
-      "CustomName",
-      "CustomNameVisible",
-      "Silent",
-      "NoGravity",
-      "Glowing",
-      "TicksFrozen",
-      "HasVisualFire",
-      "Tags",
-      "Passengers",
-      // ServerPlayer#addAdditionalSaveData(CompoundTag)
-      // Intentional omissions to prevent mount loss: Attach, Entity, and RootVehicle
-      "warden_spawn_tracker",
-      "enteredNetherPosition",
-      "SpawnX",
-      "SpawnY",
-      "SpawnZ",
-      "SpawnForced",
-      "SpawnAngle",
-      "SpawnDimension",
-      "raid_omen_position",
-      "ender_pearls",
-      // Player#addAdditionalSaveData(CompoundTag)
-      "ShoulderEntityLeft",
-      "ShoulderEntityRight",
-      "LastDeathLocation",
-      "current_explosion_impact_pos",
-      // LivingEntity#addAdditionalSaveData(CompoundTag)
-      "active_effects",
-      "SleepingX",
-      "SleepingY",
-      "SleepingZ",
-      "Brain"
-  );
-
-  private final PlayerManager manager;
-
-  OpenPlayer(CraftServer server, ServerPlayer entity, PlayerManager manager) {
-    super(server, entity);
-    this.manager = manager;
-  }
-
-  @Override
-  public void loadData() {
-    manager.loadData(getHandle());
+  protected OpenPlayer(
+      CraftServer server,
+      ServerPlayer entity,
+      PlayerManager manager
+  ) {
+    super(server, entity, manager);
   }
 
   @Override
@@ -85,14 +33,18 @@ public class OpenPlayer extends CraftPlayer {
     }
 
     ServerPlayer player = this.getHandle();
+    Logger logger = LogUtils.getLogger();
     // See net.minecraft.world.level.storage.PlayerDataStorage#save(EntityHuman)
-    try {
-      PlayerDataStorage worldNBTStorage = player.server.getPlayerList().playerIo;
+    try (ProblemReporter.ScopedCollector scopedCollector = new ProblemReporter.ScopedCollector(player.problemPath(), logger)) {
+      PlayerDataStorage worldNBTStorage = server.getServer().getPlayerList().playerIo;
 
-      CompoundTag oldData = isOnline() ? null : worldNBTStorage.load(player.getName().getString(), player.getStringUUID()).orElse(null);
+      CompoundTag oldData = isOnline()
+          ? null
+          : worldNBTStorage.load(player.getName().getString(), player.getStringUUID(), scopedCollector).orElse(null);
       CompoundTag playerData = getWritableTag(oldData);
-      playerData = player.saveWithoutId(playerData);
-      setExtraData(playerData);
+
+      ValueOutput valueOutput = TagValueOutput.createWrappingWithContext(scopedCollector, player.registryAccess(), playerData);
+      player.saveWithoutId(valueOutput);
 
       if (oldData != null) {
         // Revert certain special data values when offline.
@@ -110,74 +62,4 @@ public class OpenPlayer extends CraftPlayer {
     }
   }
 
-  @Contract("null -> new")
-  private @NotNull CompoundTag getWritableTag(@Nullable CompoundTag oldData) {
-    if (oldData == null) {
-      return new CompoundTag();
-    }
-
-    // Copy old data. This is a deep clone, so operating on it should be safe.
-    oldData = oldData.copy();
-
-    // Remove vanilla/server data that is not written every time.
-    oldData.getAllKeys()
-        .removeIf(key -> RESET_TAGS.contains(key) || key.startsWith("Bukkit"));
-
-    return oldData;
-  }
-
-  private void revertSpecialValues(@NotNull CompoundTag newData, @NotNull CompoundTag oldData) {
-    // Revert automatic updates to play timestamps.
-    copyValue(oldData, newData, "bukkit", "lastPlayed", NumericTag.class);
-    copyValue(oldData, newData, "Paper", "LastSeen", NumericTag.class);
-    copyValue(oldData, newData, "Paper", "LastLogin", NumericTag.class);
-  }
-
-  private <T extends Tag> void copyValue(
-      @NotNull CompoundTag source,
-      @NotNull CompoundTag target,
-      @NotNull String container,
-      @NotNull String key,
-      @SuppressWarnings("SameParameterValue") @NotNull Class<T> tagType) {
-    CompoundTag oldContainer = getTag(source, container, CompoundTag.class);
-    CompoundTag newContainer = getTag(target, container, CompoundTag.class);
-
-    // New container being null means the server implementation doesn't store this data.
-    if (newContainer == null) {
-      return;
-    }
-
-    // If old tag exists, copy it to new location, removing otherwise.
-    setTag(newContainer, key, getTag(oldContainer, key, tagType));
-  }
-
-  private <T extends Tag> @Nullable T getTag(
-      @Nullable CompoundTag container,
-      @NotNull String key,
-      @NotNull Class<T> dataType) {
-    if (container == null) {
-      return null;
-    }
-    Tag value = container.get(key);
-    if (value == null || !dataType.isAssignableFrom(value.getClass())) {
-      return null;
-    }
-    return dataType.cast(value);
-  }
-
-  private <T extends Tag> void setTag(
-      @NotNull CompoundTag container,
-      @NotNull String key,
-      @Nullable T data) {
-    if (data == null) {
-      container.remove(key);
-    } else {
-      container.put(key, data);
-    }
-  }
-
-  public static boolean isConnected(@Nullable ServerGamePacketListenerImpl connection) {
-    return connection != null && !connection.isDisconnected();
-  }
-
 }

internal/common/src/main/java/com/lishid/openinv/internal/common/player/PlayerManager.java

@@ -3,11 +3,9 @@ package com.lishid.openinv.internal.common.player;
 import com.lishid.openinv.internal.ISpecialInventory;
 import com.lishid.openinv.internal.common.container.OpenEnderChest;
 import com.lishid.openinv.internal.common.container.OpenInventory;
+import com.lishid.openinv.util.JulLoggerAdapter;
 import com.mojang.authlib.GameProfile;
-import com.mojang.serialization.Dynamic;
 import io.papermc.paper.adventure.PaperAdventure;
-import net.minecraft.nbt.CompoundTag;
-import net.minecraft.nbt.NbtOps;
 import net.minecraft.network.chat.Component;
 import net.minecraft.network.protocol.game.ClientboundOpenScreenPacket;
 import net.minecraft.server.MinecraftServer;
@@ -15,11 +13,12 @@ import net.minecraft.server.level.ClientInformation;
 import net.minecraft.server.level.ParticleStatus;
 import net.minecraft.server.level.ServerLevel;
 import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.util.ProblemReporter;
 import net.minecraft.world.entity.Entity;
 import net.minecraft.world.entity.player.ChatVisiblity;
 import net.minecraft.world.inventory.AbstractContainerMenu;
 import net.minecraft.world.level.Level;
-import net.minecraft.world.level.dimension.DimensionType;
+import net.minecraft.world.level.storage.ValueInput;
 import org.bukkit.Bukkit;
 import org.bukkit.OfflinePlayer;
 import org.bukkit.Server;
@@ -34,13 +33,14 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.lang.reflect.Field;
+import java.util.Optional;
 import java.util.UUID;
 import java.util.logging.Logger;
 
 public class PlayerManager implements com.lishid.openinv.internal.PlayerManager {
 
   protected final @NotNull Logger logger;
-  private @Nullable Field bukkitEntity;
+  protected @Nullable Field bukkitEntity;
 
   public PlayerManager(@NotNull Logger logger) {
     this.logger = logger;
@@ -54,15 +54,15 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
   }
 
   public static @NotNull ServerPlayer getHandle(final Player player) {
-    if (player instanceof CraftPlayer) {
-      return ((CraftPlayer) player).getHandle();
+    if (player instanceof CraftPlayer craftPlayer) {
+      return craftPlayer.getHandle();
     }
 
     Server server = player.getServer();
     ServerPlayer nmsPlayer = null;
 
-    if (server instanceof CraftServer) {
-      nmsPlayer = ((CraftServer) server).getHandle().getPlayer(player.getUniqueId());
+    if (server instanceof CraftServer craftServer) {
+      nmsPlayer = craftServer.getHandle().getPlayer(player.getUniqueId());
     }
 
     if (nmsPlayer == null) {
@@ -75,7 +75,11 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
 
   @Override
   public @Nullable Player loadPlayer(@NotNull final OfflinePlayer offline) {
-    MinecraftServer server = ((CraftServer) Bukkit.getServer()).getServer();
+    if (!(Bukkit.getServer() instanceof CraftServer craftServer)) {
+      return null;
+    }
+
+    MinecraftServer server = craftServer.getServer();
     ServerLevel worldServer = server.getLevel(Level.OVERWORLD);
 
     if (worldServer == null) {
@@ -89,7 +93,7 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
     entity.getAdvancements().stopListening();
 
     // Try to load the player's data.
-    if (loadData(entity)) {
+    if (loadData(server, entity)) {
       // If data is loaded successfully, return the Bukkit entity.
       return entity.getBukkitEntity();
     }
@@ -100,11 +104,13 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
   protected @NotNull ServerPlayer createNewPlayer(
       @NotNull MinecraftServer server,
       @NotNull ServerLevel worldServer,
-      @NotNull final OfflinePlayer offline) {
+      @NotNull final OfflinePlayer offline
+  ) {
     // See net.minecraft.server.players.PlayerList#canPlayerLogin(ServerLoginPacketListenerImpl, GameProfile)
     // See net.minecraft.server.network.ServerLoginPacketListenerImpl#handleHello(ServerboundHelloPacket)
     GameProfile profile = new GameProfile(offline.getUniqueId(),
-        offline.getName() != null ? offline.getName() : offline.getUniqueId().toString());
+        offline.getName() != null ? offline.getName() : offline.getUniqueId().toString()
+    );
 
     ClientInformation dummyInfo = new ClientInformation(
         "en_us",
@@ -121,106 +127,117 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
     ServerPlayer entity = new ServerPlayer(server, worldServer, profile, dummyInfo);
 
     try {
-      injectPlayer(entity);
+      injectPlayer(server, entity);
     } catch (IllegalAccessException e) {
       logger.log(
           java.util.logging.Level.WARNING,
           e,
-          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!");
+          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!"
+      );
     }
 
     return entity;
   }
 
-  boolean loadData(@NotNull ServerPlayer player) {
+  protected boolean loadData(@NotNull MinecraftServer server, @NotNull ServerPlayer player) {
     // See CraftPlayer#loadData
-    CompoundTag loadedData = player.server.getPlayerList().playerIo.load(player).orElse(null);
 
-    if (loadedData == null) {
-      // Exceptions with loading are logged by Mojang.
-      return false;
+    try (ProblemReporter.ScopedCollector scopedCollector = new ProblemReporter.ScopedCollector(player.problemPath(), new JulLoggerAdapter(logger))) {
+      ValueInput loadedData = server.getPlayerList().playerIo.load(player, scopedCollector).orElse(null);
+
+      if (loadedData == null) {
+        // Exceptions with loading are logged.
+        return false;
+      }
+
+      // Read basic data into the player.
+      player.load(loadedData);
+      // Game type settings are loaded separately.
+      player.loadGameTypes(loadedData);
+
+      // World is not loaded by ServerPlayer#load(CompoundTag) on Paper.
+      parseWorld(server, player, loadedData);
     }
 
-    // Read basic data into the player.
-    player.load(loadedData);
-    // Also read "extra" data.
-    player.readAdditionalSaveData(loadedData);
-    // Game type settings are also loaded separately.
-    player.loadGameTypes(loadedData);
-
-    // World is not loaded by ServerPlayer#load(CompoundTag) on Paper.
-    parseWorld(player, loadedData);
-
     return true;
   }
 
-  private void parseWorld(@NotNull ServerPlayer player, @NotNull CompoundTag loadedData) {
+  private void parseWorld(@NotNull MinecraftServer server, @NotNull ServerPlayer player, @NotNull ValueInput loadedData) {
     // See PlayerList#placeNewPlayer
     World bukkitWorld;
-    if (loadedData.contains("WorldUUIDMost") && loadedData.contains("WorldUUIDLeast")) {
+    Optional<Long> msbs = loadedData.getLong("WorldUUIDMost");
+    Optional<Long> lsbs = loadedData.getLong("WorldUUIDLeast");
+    if (msbs.isPresent() && lsbs.isPresent()) {
       // Modern Bukkit world.
-      bukkitWorld = Bukkit.getServer().getWorld(new UUID(loadedData.getLong("WorldUUIDMost"), loadedData.getLong("WorldUUIDLeast")));
-    } else if (loadedData.contains("world", net.minecraft.nbt.Tag.TAG_STRING)) {
-      // Legacy Bukkit world.
-      bukkitWorld = Bukkit.getServer().getWorld(loadedData.getString("world"));
+      bukkitWorld = Bukkit.getServer().getWorld(new UUID(msbs.get(), lsbs.get()));
     } else {
-      // Vanilla player data.
-      DimensionType.parseLegacy(new Dynamic<>(NbtOps.INSTANCE, loadedData.get("Dimension")))
-          .resultOrPartial(logger::warning)
-          .map(player.server::getLevel)
-          // If ServerLevel exists, set, otherwise move to spawn.
-          .ifPresentOrElse(player::setServerLevel, () -> spawnInDefaultWorld(player));
-      return;
+      bukkitWorld = loadedData.getString("world").map(Bukkit::getWorld).orElse(null);
     }
     if (bukkitWorld == null) {
-      spawnInDefaultWorld(player);
+      spawnInDefaultWorld(server, player);
       return;
     }
     player.setServerLevel(((CraftWorld) bukkitWorld).getHandle());
   }
 
-  private void spawnInDefaultWorld(ServerPlayer player) {
-    ServerLevel level = player.server.getLevel(Level.OVERWORLD);
+  protected void spawnInDefaultWorld(@NotNull MinecraftServer server, @NotNull ServerPlayer player) {
+    ServerLevel level = server.getLevel(Level.OVERWORLD);
     if (level != null) {
+      // Adjust player to default spawn (in keeping with Paper handling) when world not found.
+      player.snapTo(player.adjustSpawnLocation(level, level.getSharedSpawnPos()).getBottomCenter(), level.getSharedSpawnAngle(), 0.0F);
       player.spawnIn(level);
     } else {
       logger.warning("Tried to load player with invalid world when no fallback was available!");
     }
   }
 
-  protected void injectPlayer(ServerPlayer player) throws IllegalAccessException {
+  protected void injectPlayer(@NotNull MinecraftServer server, @NotNull ServerPlayer player) throws IllegalAccessException {
     if (bukkitEntity == null) {
       return;
     }
 
     bukkitEntity.setAccessible(true);
 
-    bukkitEntity.set(player, new OpenPlayer(player.server.server, player, this));
+    bukkitEntity.set(player, new OpenPlayer(server.server, player, this));
   }
 
   @Override
   public @NotNull Player inject(@NotNull Player player) {
     try {
       ServerPlayer nmsPlayer = getHandle(player);
-      if (nmsPlayer.getBukkitEntity() instanceof OpenPlayer openPlayer) {
+      if (nmsPlayer.getBukkitEntity() instanceof BaseOpenPlayer openPlayer) {
         return openPlayer;
       }
-      injectPlayer(nmsPlayer);
+      MinecraftServer server = nmsPlayer.getServer();
+      if (server == null) {
+        if (!(Bukkit.getServer() instanceof CraftServer craftServer)) {
+          logger.warning(() ->
+              "Unable to inject ServerPlayer, certain player data may be lost when saving! Server is not a CraftServer: "
+                  + Bukkit.getServer().getClass().getName());
+          return player;
+        }
+        server = craftServer.getServer();
+      }
+      injectPlayer(server, nmsPlayer);
       return nmsPlayer.getBukkitEntity();
     } catch (IllegalAccessException e) {
       logger.log(
           java.util.logging.Level.WARNING,
           e,
-          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!");
+          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!"
+      );
       return player;
     }
   }
 
   @Override
-  public @Nullable InventoryView openInventory(@NotNull Player bukkitPlayer, @NotNull ISpecialInventory inventory, boolean viewOnly) {
+  public @Nullable InventoryView openInventory(
+      @NotNull Player bukkitPlayer, @NotNull ISpecialInventory inventory,
+      boolean viewOnly
+  ) {
     ServerPlayer player = getHandle(bukkitPlayer);
 
-    if (!OpenPlayer.isConnected(player.connection)) {
+    if (!BaseOpenPlayer.isConnected(player.connection)) {
       return null;
     }
 

internal/paper1_21_1/build.gradle.kts

@@ -6,8 +6,8 @@ plugins {
 configurations.all {
   resolutionStrategy.capabilitiesResolution.withCapability("org.spigotmc:spigot-api") {
     val paper = candidates.firstOrNull {
-      it.id.let {
-        id -> id is ModuleComponentIdentifier && id.module == "paper-api"
+      it.id.let { id ->
+        id is ModuleComponentIdentifier && id.module == "paper-api"
       }
     }
     if (paper != null) {
@@ -21,6 +21,8 @@ dependencies {
   implementation(project(":openinvapi"))
   implementation(project(":openinvcommon"))
   implementation(project(":openinvadaptercommon"))
+  implementation(project(":openinvadapterpaper1_21_5"))
+  implementation(project(":openinvadapterpaper1_21_4"))
   implementation(project(":openinvadapterpaper1_21_3"))
 
   paperweight.paperDevBundle("1.21.1-R0.1-SNAPSHOT")

internal/paper1_21_1/src/main/java/com/lishid/openinv/internal/paper1_21_1/InternalAccessor.java

@@ -6,10 +6,10 @@ import com.lishid.openinv.internal.ISpecialEnderChest;
 import com.lishid.openinv.internal.ISpecialInventory;
 import com.lishid.openinv.internal.ISpecialPlayerInventory;
 import com.lishid.openinv.internal.common.container.AnySilentContainer;
-import com.lishid.openinv.internal.common.container.OpenEnderChest;
 import com.lishid.openinv.internal.paper1_21_1.container.OpenInventory;
 import com.lishid.openinv.internal.paper1_21_1.container.slot.placeholder.PlaceholderLoader;
 import com.lishid.openinv.internal.paper1_21_1.player.PlayerManager;
+import com.lishid.openinv.internal.paper1_21_4.container.OpenEnderChest;
 import com.lishid.openinv.util.lang.LanguageManager;
 import net.minecraft.world.Container;
 import org.bukkit.configuration.ConfigurationSection;

internal/paper1_21_1/src/main/java/com/lishid/openinv/internal/paper1_21_1/container/OpenInventory.java

@@ -6,7 +6,7 @@ import net.minecraft.server.level.ServerPlayer;
 import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 
-public class OpenInventory extends com.lishid.openinv.internal.common.container.OpenInventory {
+public class OpenInventory extends com.lishid.openinv.internal.paper1_21_4.container.OpenInventory {
 
   public OpenInventory(@NotNull Player bukkitPlayer) {
     super(bukkitPlayer);

internal/paper1_21_1/src/main/java/com/lishid/openinv/internal/paper1_21_1/container/slot/placeholder/PlaceholderLoader.java

@@ -28,11 +28,16 @@ public class PlaceholderLoader extends NumericDataPlaceholderLoader {
     BannerPattern halfDiagBottomRight = bannerPatterns.getOrThrow(BannerPatterns.DIAGONAL_RIGHT);
     BannerPattern downRight = bannerPatterns.getOrThrow(BannerPatterns.STRIPE_DOWNRIGHT);
     BannerPattern border = bannerPatterns.getOrThrow(BannerPatterns.BORDER);
-    itemStack.set(DataComponents.BANNER_PATTERNS,
-        new BannerPatternLayers(List.of(
-            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(halfDiagBottomRight), DyeColor.GRAY),
-            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(downRight), DyeColor.WHITE),
-            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(border), DyeColor.GRAY))));
+    itemStack.set(
+        DataComponents.BANNER_PATTERNS,
+        new BannerPatternLayers(
+            List.of(
+                new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(halfDiagBottomRight), DyeColor.GRAY),
+                new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(downRight), DyeColor.WHITE),
+                new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(border), DyeColor.GRAY)
+            )
+        )
+    );
     addModelData(itemStack);
     itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
     return itemStack;
@@ -51,12 +56,16 @@ public class PlaceholderLoader extends NumericDataPlaceholderLoader {
     BannerPattern bottomLeft = bannerPatterns.getOrThrow(BannerPatterns.SQUARE_BOTTOM_LEFT);
     BannerPattern bottomRight = bannerPatterns.getOrThrow(BannerPatterns.SQUARE_BOTTOM_RIGHT);
     itemStack.set(DataComponents.BANNER_PATTERNS,
-        new BannerPatternLayers(List.of(
-            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(halfLeft), DyeColor.BLACK),
-            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(topLeft), DyeColor.MAGENTA),
-            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(bottomLeft), DyeColor.MAGENTA),
-            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(topRight), DyeColor.BLACK),
-            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(bottomRight), DyeColor.BLACK))));
+        new BannerPatternLayers(
+            List.of(
+                new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(halfLeft), DyeColor.BLACK),
+                new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(topLeft), DyeColor.MAGENTA),
+                new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(bottomLeft), DyeColor.MAGENTA),
+                new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(topRight), DyeColor.BLACK),
+                new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(bottomRight), DyeColor.BLACK)
+            )
+        )
+    );
     itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
     addModelData(itemStack);
     return itemStack;

internal/paper1_21_1/src/main/java/com/lishid/openinv/internal/paper1_21_1/player/PlayerManager.java

@@ -11,7 +11,8 @@ import org.jetbrains.annotations.NotNull;
 
 import java.util.logging.Logger;
 
-public class PlayerManager extends com.lishid.openinv.internal.common.player.PlayerManager {
+public class PlayerManager extends com.lishid.openinv.internal.paper1_21_4.player.PlayerManager {
+
   public PlayerManager(@NotNull Logger logger) {
     super(logger);
   }
@@ -20,11 +21,13 @@ public class PlayerManager extends com.lishid.openinv.internal.common.player.Pla
   protected @NotNull ServerPlayer createNewPlayer(
       @NotNull MinecraftServer server,
       @NotNull ServerLevel worldServer,
-      @NotNull final OfflinePlayer offline) {
+      @NotNull final OfflinePlayer offline
+  ) {
     // See net.minecraft.server.players.PlayerList#canPlayerLogin(ServerLoginPacketListenerImpl, GameProfile)
     // See net.minecraft.server.network.ServerLoginPacketListenerImpl#handleHello(ServerboundHelloPacket)
     GameProfile profile = new GameProfile(offline.getUniqueId(),
-        offline.getName() != null ? offline.getName() : offline.getUniqueId().toString());
+        offline.getName() != null ? offline.getName() : offline.getUniqueId().toString()
+    );
 
     ClientInformation dummyInfo = new ClientInformation(
         "en_us",
@@ -40,12 +43,13 @@ public class PlayerManager extends com.lishid.openinv.internal.common.player.Pla
     ServerPlayer entity = new ServerPlayer(server, worldServer, profile, dummyInfo);
 
     try {
-      injectPlayer(entity);
+      injectPlayer(server, entity);
     } catch (IllegalAccessException e) {
       logger.log(
           java.util.logging.Level.WARNING,
           e,
-          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!");
+          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!"
+      );
     }
 
     return entity;

internal/paper1_21_3/build.gradle.kts

@@ -6,8 +6,8 @@ plugins {
 configurations.all {
   resolutionStrategy.capabilitiesResolution.withCapability("org.spigotmc:spigot-api") {
     val paper = candidates.firstOrNull {
-      it.id.let {
-        id -> id is ModuleComponentIdentifier && id.module == "paper-api"
+      it.id.let { id ->
+        id is ModuleComponentIdentifier && id.module == "paper-api"
       }
     }
     if (paper != null) {
@@ -21,6 +21,8 @@ dependencies {
   implementation(project(":openinvapi"))
   implementation(project(":openinvcommon"))
   implementation(project(":openinvadaptercommon"))
+  implementation(project(":openinvadapterpaper1_21_5"))
+  implementation(project(":openinvadapterpaper1_21_4"))
 
   paperweight.paperDevBundle("1.21.3-R0.1-SNAPSHOT")
 }

internal/paper1_21_3/src/main/java/com/lishid/openinv/internal/paper1_21_3/InternalAccessor.java

@@ -8,7 +8,7 @@ import org.jetbrains.annotations.NotNull;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
-public class InternalAccessor extends com.lishid.openinv.internal.common.InternalAccessor {
+public class InternalAccessor extends com.lishid.openinv.internal.paper1_21_4.InternalAccessor {
 
   public InternalAccessor(@NotNull Logger logger, @NotNull LanguageManager lang) {
     super(logger, lang);

internal/paper1_21_3/src/main/java/com/lishid/openinv/internal/paper1_21_3/container/slot/placeholder/NumericDataPlaceholderLoader.java

@@ -1,31 +1,12 @@
 package com.lishid.openinv.internal.paper1_21_3.container.slot.placeholder;
 
-import com.lishid.openinv.internal.common.container.slot.placeholder.PlaceholderLoaderBase;
-import net.minecraft.core.HolderLookup;
-import net.minecraft.core.Registry;
-import net.minecraft.core.RegistryAccess;
-import net.minecraft.core.component.DataComponents;
-import net.minecraft.core.registries.Registries;
-import net.minecraft.util.Unit;
-import net.minecraft.world.item.DyeColor;
-import net.minecraft.world.item.ItemStack;
-import net.minecraft.world.item.Items;
+import com.lishid.openinv.internal.paper1_21_4.container.slot.placeholder.CustomModelBase;
 import net.minecraft.world.item.component.CustomModelData;
-import net.minecraft.world.level.block.entity.BannerPattern;
-import net.minecraft.world.level.block.entity.BannerPatternLayers;
-import net.minecraft.world.level.block.entity.BannerPatterns;
-import org.bukkit.craftbukkit.CraftRegistry;
-import org.jetbrains.annotations.NotNull;
 
-import java.util.List;
+public class NumericDataPlaceholderLoader extends CustomModelBase {
 
-public class NumericDataPlaceholderLoader extends PlaceholderLoaderBase {
-
-  private static final CustomModelData DEFAULT_CUSTOM_MODEL_DATA = new CustomModelData(9999);
-
-  @Override
-  protected void addModelData(ItemStack itemStack) {
-    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+  public NumericDataPlaceholderLoader() {
+    super(new CustomModelData(9999));
   }
 
 }

internal/paper1_21_4/build.gradle.kts

@@ -0,0 +1,27 @@
+plugins {
+  `openinv-base`
+  alias(libs.plugins.paperweight)
+}
+
+configurations.all {
+  resolutionStrategy.capabilitiesResolution.withCapability("org.spigotmc:spigot-api") {
+    val paper = candidates.firstOrNull {
+      it.id.let { id ->
+        id is ModuleComponentIdentifier && id.module == "paper-api"
+      }
+    }
+    if (paper != null) {
+      select(paper)
+    }
+    because("module is written for Paper servers")
+  }
+}
+
+dependencies {
+  implementation(project(":openinvapi"))
+  implementation(project(":openinvcommon"))
+  implementation(project(":openinvadaptercommon"))
+  implementation(project(":openinvadapterpaper1_21_5"))
+
+  paperweight.paperDevBundle("1.21.4-R0.1-SNAPSHOT")
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/InternalAccessor.java

@@ -0,0 +1,80 @@
+package com.lishid.openinv.internal.paper1_21_4;
+
+import com.lishid.openinv.internal.Accessor;
+import com.lishid.openinv.internal.IAnySilentContainer;
+import com.lishid.openinv.internal.ISpecialEnderChest;
+import com.lishid.openinv.internal.ISpecialInventory;
+import com.lishid.openinv.internal.ISpecialPlayerInventory;
+import com.lishid.openinv.internal.common.container.AnySilentContainer;
+import com.lishid.openinv.internal.paper1_21_4.container.OpenEnderChest;
+import com.lishid.openinv.internal.paper1_21_4.container.OpenInventory;
+import com.lishid.openinv.internal.paper1_21_4.container.slot.placeholder.CustomModelPlaceholderLoader;
+import com.lishid.openinv.internal.paper1_21_4.player.PlayerManager;
+import com.lishid.openinv.util.lang.LanguageManager;
+import net.minecraft.world.Container;
+import org.bukkit.configuration.ConfigurationSection;
+import org.bukkit.craftbukkit.inventory.CraftInventory;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.Inventory;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class InternalAccessor implements Accessor {
+
+  protected final @NotNull Logger logger;
+  private final @NotNull PlayerManager manager;
+  private final @NotNull AnySilentContainer anySilentContainer;
+
+  public InternalAccessor(@NotNull Logger logger, @NotNull LanguageManager lang) {
+    this.logger = logger;
+    manager = new PlayerManager(logger);
+    anySilentContainer = new AnySilentContainer(logger, lang);
+  }
+
+  @Override
+  public @NotNull PlayerManager getPlayerManager() {
+    return manager;
+  }
+
+  @Override
+  public @NotNull IAnySilentContainer getAnySilentContainer() {
+    return anySilentContainer;
+  }
+
+  @Override
+  public @NotNull ISpecialPlayerInventory createPlayerInventory(@NotNull Player player) {
+    return new OpenInventory(player);
+  }
+
+  @Override
+  public @NotNull ISpecialEnderChest createEnderChest(@NotNull Player player) {
+    return new OpenEnderChest(player);
+  }
+
+  @Override
+  public <T extends ISpecialInventory> @Nullable T get(@NotNull Inventory bukkitInventory, @NotNull Class<T> clazz) {
+    if (!(bukkitInventory instanceof CraftInventory craftInventory)) {
+      return null;
+    }
+    Container container = craftInventory.getInventory();
+    if (clazz.isInstance(container)) {
+      return clazz.cast(container);
+    }
+    return null;
+  }
+
+  @Override
+  public void reload(@NotNull ConfigurationSection config) {
+    ConfigurationSection placeholders = config.getConfigurationSection("placeholders");
+    try {
+      // Reset placeholders to defaults and try to load configuration.
+      new CustomModelPlaceholderLoader().load(placeholders);
+    } catch (Exception e) {
+      logger.log(Level.WARNING, "Caught exception loading placeholder overrides!", e);
+    }
+  }
+
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/container/OpenEnderChest.java

@@ -0,0 +1,28 @@
+package com.lishid.openinv.internal.paper1_21_4.container;
+
+import com.lishid.openinv.internal.paper1_21_4.container.menu.OpenEnderChestMenu;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class OpenEnderChest extends com.lishid.openinv.internal.common.container.OpenEnderChest {
+
+  public OpenEnderChest(@NotNull Player player) {
+    super(player);
+  }
+
+  @Override
+  public @Nullable AbstractContainerMenu createMenu(
+      net.minecraft.world.entity.player.Player player,
+      int i,
+      boolean viewOnly
+  ) {
+    if (player instanceof ServerPlayer serverPlayer) {
+      return new OpenEnderChestMenu(this, serverPlayer, i, viewOnly);
+    }
+    return null;
+  }
+
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/container/OpenInventory.java

@@ -0,0 +1,191 @@
+package com.lishid.openinv.internal.paper1_21_4.container;
+
+import com.lishid.openinv.internal.common.container.slot.ContentCrafting;
+import com.lishid.openinv.internal.common.container.slot.ContentCursor;
+import com.lishid.openinv.internal.common.container.slot.ContentDrop;
+import com.lishid.openinv.internal.common.container.slot.ContentList;
+import com.lishid.openinv.internal.common.container.slot.ContentViewOnly;
+import com.lishid.openinv.internal.common.container.slot.SlotViewOnly;
+import com.lishid.openinv.internal.common.container.slot.placeholder.Placeholders;
+import com.lishid.openinv.internal.paper1_21_4.container.bukkit.OpenPlayerInventory;
+import com.lishid.openinv.internal.paper1_21_4.container.menu.OpenInventoryMenu;
+import com.lishid.openinv.internal.paper1_21_4.container.slot.ContentEquipment;
+import com.lishid.openinv.internal.paper1_21_4.container.slot.ContentOffHand;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.entity.player.Inventory;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class OpenInventory extends com.lishid.openinv.internal.common.container.OpenInventory {
+
+  public OpenInventory(@NotNull org.bukkit.entity.Player bukkitPlayer) {
+    super(bukkitPlayer);
+  }
+
+  @Override
+  protected void setupSlots() {
+    // Top of inventory: Regular contents.
+    int nextIndex = addMainInventory();
+
+    // If inventory is expected size, we can arrange slots to be pretty.
+    Inventory ownerInv = owner.getInventory();
+    if (ownerInv.items.size() == 36
+        && ownerInv.armor.size() == 4
+        && ownerInv.offhand.size() == 1
+        && owner.inventoryMenu.getCraftSlots().getContainerSize() == 4) {
+      // Armor slots: Bottom left.
+      addArmor(36);
+      // Off-hand: Below chestplate.
+      addOffHand(46);
+      // Drop slot: Bottom right.
+      slots.set(53, new ContentDrop(owner));
+      // Cursor slot: Above drop.
+      slots.set(44, new ContentCursor(owner));
+
+      // Crafting is displayed in the bottom right corner.
+      // As we're using the pretty view, this is a 3x2.
+      addCrafting(41, true);
+      return;
+    }
+
+    // Otherwise we'll just add elements linearly.
+    nextIndex = addArmor(nextIndex);
+    nextIndex = addOffHand(nextIndex);
+    nextIndex = addCrafting(nextIndex, false);
+    slots.set(nextIndex, new ContentCursor(owner));
+    // Drop slot last.
+    slots.set(slots.size() - 1, new ContentDrop(owner));
+  }
+
+  private int addMainInventory() {
+    int listSize = owner.getInventory().items.size();
+    // Hotbar slots are 0-8. We want those to appear on the bottom of the inventory like a normal player inventory,
+    // so everything else needs to move up a row.
+    int hotbarDiff = listSize - 9;
+    for (int localIndex = 0; localIndex < listSize; ++localIndex) {
+      InventoryType.SlotType type;
+      int invIndex;
+      if (localIndex < hotbarDiff) {
+        invIndex = localIndex + 9;
+        type = InventoryType.SlotType.CONTAINER;
+      } else {
+        type = InventoryType.SlotType.QUICKBAR;
+        invIndex = localIndex - hotbarDiff;
+      }
+
+      slots.set(
+          localIndex,
+          new ContentList(owner, invIndex, type) {
+            @Override
+            public void setHolder(@NotNull ServerPlayer holder) {
+              items = holder.getInventory().items;
+            }
+          }
+      );
+    }
+    return listSize;
+  }
+
+  private int addArmor(int startIndex) {
+    int listSize = owner.getInventory().armor.size();
+
+    for (int i = 0; i < listSize; ++i) {
+      // Armor slots go bottom to top; boots are slot 0, helmet is slot 3.
+      // Since we have to display horizontally due to space restrictions,
+      // making the left side the "top" is more user-friendly.
+      int armorIndex;
+      EquipmentSlot slot;
+      switch (i) {
+        case 3 -> {
+          armorIndex = 0;
+          slot = EquipmentSlot.FEET;
+        }
+        case 2 -> {
+          armorIndex = 1;
+          slot = EquipmentSlot.LEGS;
+        }
+        case 1 -> {
+          armorIndex = 2;
+          slot = EquipmentSlot.CHEST;
+        }
+        case 0 -> {
+          armorIndex = 3;
+          slot = EquipmentSlot.HEAD;
+        }
+        default -> {
+          // In the event that new armor slots are added, they can be placed at the end.
+          armorIndex = i;
+          slot = EquipmentSlot.MAINHAND;
+        }
+      }
+
+      slots.set(startIndex + i, new ContentEquipment(owner, armorIndex, slot));
+    }
+
+    return startIndex + listSize;
+  }
+
+  private int addOffHand(int startIndex) {
+    int listSize = owner.getInventory().offhand.size();
+    for (int localIndex = 0; localIndex < listSize; ++localIndex) {
+      slots.set(startIndex + localIndex, new ContentOffHand(owner, localIndex));
+    }
+    return startIndex + listSize;
+  }
+
+  private int addCrafting(int startIndex, boolean pretty) {
+    int listSize = owner.inventoryMenu.getCraftSlots().getContents().size();
+    pretty &= listSize == 4;
+
+    for (int localIndex = 0; localIndex < listSize; ++localIndex) {
+      // Pretty display is a 2x2 rather than linear.
+      // If index is in top row, grid is not 2x2, or pretty is disabled, just use current index.
+      // Otherwise, subtract 2 and add 9 to start in the same position on the next row.
+      int modIndex = startIndex + (localIndex < 2 || !pretty ? localIndex : localIndex + 7);
+
+      slots.set(modIndex, new ContentCrafting(owner, localIndex));
+    }
+
+    if (pretty) {
+      slots.set(startIndex + 2, new ContentViewOnly(owner) {
+            @Override
+            public Slot asSlot(Container container, int slot, int x, int y) {
+              return new SlotViewOnly(container, slot, x, y) {
+                @Override
+                public ItemStack getOrDefault() {
+                  return Placeholders.craftingOutput;
+                }
+              };
+            }
+          }
+      );
+      slots.set(startIndex + 11, getCraftingResult(owner));
+    }
+
+    return startIndex + listSize;
+  }
+
+  @Override
+  public @NotNull org.bukkit.inventory.Inventory getBukkitInventory() {
+    if (bukkitEntity == null) {
+      bukkitEntity = new OpenPlayerInventory(this);
+    }
+    return bukkitEntity;
+  }
+
+  @Override
+  public @Nullable AbstractContainerMenu createMenu(Player player, int i, boolean viewOnly) {
+    if (player instanceof ServerPlayer serverPlayer) {
+      return new OpenInventoryMenu(this, serverPlayer, i, viewOnly);
+    }
+    return null;
+  }
+
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/container/bukkit/OpenPlayerInventory.java

@@ -0,0 +1,225 @@
+package com.lishid.openinv.internal.paper1_21_4.container.bukkit;
+
+import com.google.common.base.Preconditions;
+import com.lishid.openinv.internal.paper1_21_4.container.OpenInventory;
+import net.minecraft.core.NonNullList;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.entity.player.Inventory;
+import org.bukkit.craftbukkit.inventory.CraftInventory;
+import org.bukkit.craftbukkit.inventory.CraftItemStack;
+import org.bukkit.entity.Player;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.PlayerInventory;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class OpenPlayerInventory extends CraftInventory implements PlayerInventory {
+
+  public OpenPlayerInventory(@NotNull OpenInventory inventory) {
+    super(inventory);
+  }
+
+  @Override
+  public @NotNull OpenInventory getInventory() {
+    return (OpenInventory) super.getInventory();
+  }
+
+  @Override
+  public ItemStack @NotNull [] getContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().getContents());
+  }
+
+  @Override
+  public void setContents(ItemStack[] items) {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    int size = internal.getContainerSize();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+
+    for (int index = 0; index < size; ++index) {
+      if (index < items.length) {
+        internal.setItem(index, CraftItemStack.asNMSCopy(items[index]));
+      } else {
+        internal.setItem(index, net.minecraft.world.item.ItemStack.EMPTY);
+      }
+    }
+  }
+
+  @Override
+  public ItemStack @NotNull [] getStorageContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().items);
+  }
+
+  @Override
+  public void setStorageContents(ItemStack[] items) throws IllegalArgumentException {
+    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().items;
+    int size = list.size();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+    for (int index = 0; index < items.length; ++index) {
+      list.set(index, CraftItemStack.asNMSCopy(items[index]));
+    }
+  }
+
+  @Override
+  public @NotNull InventoryType getType() {
+    return InventoryType.PLAYER;
+  }
+
+  @Override
+  public @NotNull Player getHolder() {
+    return getInventory().getOwner();
+  }
+
+  @Override
+  public @NotNull ItemStack @NotNull [] getArmorContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().armor);
+  }
+
+  @Override
+  public void setArmorContents(ItemStack @NotNull [] items) {
+    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().armor;
+    int size = list.size();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+    for (int index = 0; index < items.length; ++index) {
+      list.set(index, CraftItemStack.asNMSCopy(items[index]));
+    }
+  }
+
+  @Override
+  public @NotNull ItemStack @NotNull [] getExtraContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().offhand);
+  }
+
+  @Override
+  public void setExtraContents(ItemStack @NotNull [] items) {
+    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().offhand;
+    int size = list.size();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+    for (int index = 0; index < items.length; ++index) {
+      list.set(index, CraftItemStack.asNMSCopy(items[index]));
+    }
+  }
+
+  @Override
+  public @NotNull ItemStack getHelmet() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
+        .getArmor(EquipmentSlot.HEAD.getIndex()));
+  }
+
+  @Override
+  public void setHelmet(@Nullable ItemStack helmet) {
+    getInventory().getOwnerHandle().getInventory().armor
+        .set(EquipmentSlot.HEAD.getIndex(), CraftItemStack.asNMSCopy(helmet));
+  }
+
+  @Override
+  public @NotNull ItemStack getChestplate() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
+        .getArmor(EquipmentSlot.CHEST.getIndex()));
+  }
+
+  @Override
+  public void setChestplate(@Nullable ItemStack chestplate) {
+    getInventory().getOwnerHandle().getInventory().armor
+        .set(EquipmentSlot.CHEST.getIndex(), CraftItemStack.asNMSCopy(chestplate));
+  }
+
+  @Override
+  public @NotNull ItemStack getLeggings() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
+        .getArmor(EquipmentSlot.LEGS.getIndex()));
+  }
+
+  @Override
+  public void setLeggings(@Nullable ItemStack leggings) {
+    getInventory().getOwnerHandle().getInventory().armor
+        .set(EquipmentSlot.LEGS.getIndex(), CraftItemStack.asNMSCopy(leggings));
+  }
+
+  @Override
+  public @NotNull ItemStack getBoots() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
+        .getArmor(EquipmentSlot.FEET.getIndex()));
+  }
+
+  @Override
+  public void setBoots(@Nullable ItemStack boots) {
+    getInventory().getOwnerHandle().getInventory().armor
+        .set(EquipmentSlot.FEET.getIndex(), CraftItemStack.asNMSCopy(boots));
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInMainHand() {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    return CraftItemStack.asCraftMirror(internal.getItem(internal.selected));
+  }
+
+  @Override
+  public void setItemInMainHand(@Nullable ItemStack item) {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    internal.setItem(internal.selected, CraftItemStack.asNMSCopy(item));
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInOffHand() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory().offhand.getFirst());
+  }
+
+  @Override
+  public void setItemInOffHand(@Nullable ItemStack item) {
+    getInventory().getOwnerHandle().getInventory().offhand.set(0, CraftItemStack.asNMSCopy(item));
+  }
+
+  @SuppressWarnings("InlineMeSuggester")
+  @Deprecated
+  @Override
+  public @NotNull ItemStack getItemInHand() {
+    return getItemInMainHand();
+  }
+
+  @SuppressWarnings("InlineMeSuggester")
+  @Deprecated
+  @Override
+  public void setItemInHand(@Nullable ItemStack stack) {
+    setItemInMainHand(stack);
+  }
+
+  @Override
+  public int getHeldItemSlot() {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    return internal.items.size() - 9 + internal.selected;
+  }
+
+  @Override
+  public void setHeldItemSlot(int slot) {
+    slot %= 9;
+    getInventory().getOwnerHandle().getInventory().selected = slot;
+  }
+
+  @Override
+  public @NotNull ItemStack getItem(@NotNull org.bukkit.inventory.EquipmentSlot slot) {
+    return switch (slot) {
+      case HAND -> getItemInMainHand();
+      case OFF_HAND -> getItemInOffHand();
+      case FEET -> getBoots();
+      case LEGS -> getLeggings();
+      case CHEST -> getChestplate();
+      case HEAD -> getHelmet();
+      default -> throw new IllegalArgumentException("Unsupported EquipmentSlot " + slot);
+    };
+  }
+
+  @Override
+  public void setItem(@NotNull org.bukkit.inventory.EquipmentSlot slot, @Nullable ItemStack item) {
+    switch (slot) {
+      case HAND -> setItemInMainHand(item);
+      case OFF_HAND -> setItemInOffHand(item);
+      case FEET -> setBoots(item);
+      case LEGS -> setLeggings(item);
+      case CHEST -> setChestplate(item);
+      case HEAD -> setHelmet(item);
+      default -> throw new IllegalArgumentException("Unsupported EquipmentSlot " + slot);
+    }
+  }
+
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/container/bukkit/OpenPlayerInventorySelf.java

@@ -0,0 +1,26 @@
+package com.lishid.openinv.internal.paper1_21_4.container.bukkit;
+
+import com.lishid.openinv.internal.paper1_21_4.container.OpenInventory;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+public class OpenPlayerInventorySelf extends OpenPlayerInventory {
+
+  private final int offset;
+
+  public OpenPlayerInventorySelf(@NotNull OpenInventory inventory, int offset) {
+    super(inventory);
+    this.offset = offset;
+  }
+
+  @Override
+  public ItemStack getItem(int index) {
+    return super.getItem(offset + index);
+  }
+
+  @Override
+  public void setItem(int index, ItemStack item) {
+    super.setItem(offset + index, item);
+  }
+
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/container/menu/OpenChestMenu.java

@@ -0,0 +1,467 @@
+package com.lishid.openinv.internal.paper1_21_4.container.menu;
+
+import com.google.common.base.Suppliers;
+import com.lishid.openinv.internal.ISpecialInventory;
+import com.lishid.openinv.internal.InternalOwned;
+import com.lishid.openinv.internal.common.container.bukkit.OpenDummyInventory;
+import com.lishid.openinv.internal.common.container.slot.SlotPlaceholder;
+import com.lishid.openinv.internal.common.container.slot.SlotViewOnly;
+import it.unimi.dsi.fastutil.ints.IntArrayList;
+import it.unimi.dsi.fastutil.ints.IntList;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.inventory.ChestMenu;
+import net.minecraft.world.inventory.ClickType;
+import net.minecraft.world.inventory.ContainerData;
+import net.minecraft.world.inventory.ContainerListener;
+import net.minecraft.world.inventory.ContainerSynchronizer;
+import net.minecraft.world.inventory.DataSlot;
+import net.minecraft.world.inventory.MenuType;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.craftbukkit.inventory.CraftInventoryView;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.Inventory;
+import org.bukkit.inventory.InventoryView;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Supplier;
+
+/**
+ * An extension of {@link AbstractContainerMenu} that supports {@link SlotPlaceholder placeholders}.
+ */
+@SuppressWarnings("HidingField")
+public abstract class OpenChestMenu<T extends Container & ISpecialInventory & InternalOwned<ServerPlayer>>
+    extends AbstractContainerMenu {
+
+  protected static final int BOTTOM_INVENTORY_SIZE = 36;
+
+  protected final T container;
+  protected final ServerPlayer viewer;
+  protected final boolean viewOnly;
+  protected final boolean ownContainer;
+  protected final int topSize;
+  private CraftInventoryView<OpenChestMenu<T>, Inventory> bukkitEntity;
+  // Syncher fields
+  private @Nullable ContainerSynchronizer synchronizer;
+  private final List<DataSlot> dataSlots = new ArrayList<>();
+  private final IntList remoteDataSlots = new IntArrayList();
+  private final List<ContainerListener> containerListeners = new ArrayList<>();
+  private ItemStack remoteCarried = ItemStack.EMPTY;
+  private boolean suppressRemoteUpdates;
+
+  protected OpenChestMenu(
+      @NotNull MenuType<ChestMenu> type,
+      int containerCounter,
+      @NotNull T container,
+      @NotNull ServerPlayer viewer,
+      boolean viewOnly
+  ) {
+    super(type, containerCounter);
+    this.container = container;
+    this.viewer = viewer;
+    this.viewOnly = viewOnly;
+    ownContainer = container.getOwnerHandle().equals(viewer);
+    topSize = getTopSize(viewer);
+
+    preSlotSetup();
+
+    int upperRows = topSize / 9;
+    // View's upper inventory - our container
+    for (int row = 0; row < upperRows; ++row) {
+      for (int col = 0; col < 9; ++col) {
+        // x and y for client purposes, but hey, we're thorough here.
+        // Adapted from net.minecraft.world.inventory.ChestMenu
+        int x = 8 + col * 18;
+        int y = 18 + row * 18;
+        int index = row * 9 + col;
+
+        // Guard against weird inventory sizes.
+        if (index >= container.getContainerSize()) {
+          addSlot(new SlotViewOnly(container, index, x, y));
+          continue;
+        }
+
+        Slot slot = getUpperSlot(index, x, y);
+
+        addSlot(slot);
+      }
+    }
+
+    // View's lower inventory - viewer inventory
+    int playerInvPad = (upperRows - 4) * 18;
+    for (int row = 0; row < 3; ++row) {
+      for (int col = 0; col < 9; ++col) {
+        int x = 8 + col * 18;
+        int y = playerInvPad + row * 18 + 103;
+        addSlot(new Slot(viewer.getInventory(), row * 9 + col + 9, x, y));
+      }
+    }
+    // Hotbar
+    for (int col = 0; col < 9; ++col) {
+      int x = 8 + col * 18;
+      int y = playerInvPad + 161;
+      addSlot(new Slot(viewer.getInventory(), col, x, y));
+    }
+  }
+
+  protected void preSlotSetup() {
+  }
+
+  protected @NotNull Slot getUpperSlot(int index, int x, int y) {
+    Slot slot = new Slot(container, index, x, y);
+    if (viewOnly) {
+      return SlotViewOnly.wrap(slot);
+    }
+    return slot;
+  }
+
+
+  @Override
+  public final @NotNull CraftInventoryView<OpenChestMenu<T>, Inventory> getBukkitView() {
+    if (bukkitEntity == null) {
+      bukkitEntity = createBukkitEntity();
+    }
+
+    return bukkitEntity;
+  }
+
+  protected @NotNull CraftInventoryView<OpenChestMenu<T>, Inventory> createBukkitEntity() {
+    Inventory top;
+    if (viewOnly) {
+      top = new OpenDummyInventory(container, container.getBukkitType());
+    } else {
+      top = container.getBukkitInventory();
+    }
+    return new CraftInventoryView<>(viewer.getBukkitEntity(), top, this) {
+      @Override
+      public @Nullable Inventory getInventory(int rawSlot) {
+        if (viewOnly) {
+          return null;
+        }
+        return super.getInventory(rawSlot);
+      }
+
+      @Override
+      public int convertSlot(int rawSlot) {
+        if (viewOnly) {
+          return InventoryView.OUTSIDE;
+        }
+        return super.convertSlot(rawSlot);
+      }
+
+      @Override
+      public @NotNull InventoryType.SlotType getSlotType(int slot) {
+        if (viewOnly) {
+          return InventoryType.SlotType.OUTSIDE;
+        }
+        return super.getSlotType(slot);
+      }
+    };
+  }
+
+  private int getTopSize(ServerPlayer viewer) {
+    MenuType<?> menuType = getType();
+    if (menuType == MenuType.GENERIC_9x1) {
+      return 9;
+    } else if (menuType == MenuType.GENERIC_9x2) {
+      return 18;
+    } else if (menuType == MenuType.GENERIC_9x3) {
+      return 27;
+    } else if (menuType == MenuType.GENERIC_9x4) {
+      return 36;
+    } else if (menuType == MenuType.GENERIC_9x5) {
+      return 45;
+    } else if (menuType == MenuType.GENERIC_9x6) {
+      return 54;
+    }
+    // This is a bit gross, but allows us a safe fallthrough.
+    return menuType.create(-1, viewer.getInventory()).slots.size() - BOTTOM_INVENTORY_SIZE;
+  }
+
+  /**
+   * Reimplementation of {@link AbstractContainerMenu#moveItemStackTo(ItemStack, int, int, boolean)} that ignores fake
+   * slots and respects {@link Slot#hasItem()}.
+   *
+   * @param itemStack the stack to quick-move
+   * @param rangeLow the start of the range of slots that can be moved to, inclusive
+   * @param rangeHigh the end of the range of slots that can be moved to, exclusive
+   * @param topDown whether to start at the top of the range or bottom
+   * @return whether the stack was modified as a result of being quick-moved
+   */
+  @Override
+  protected boolean moveItemStackTo(ItemStack itemStack, int rangeLow, int rangeHigh, boolean topDown) {
+    boolean modified = false;
+    boolean stackable = itemStack.isStackable();
+    Slot firstEmpty = null;
+
+    for (int index = topDown ? rangeHigh - 1 : rangeLow;
+         !itemStack.isEmpty() && (topDown ? index >= rangeLow : index < rangeHigh);
+         index += topDown ? -1 : 1
+    ) {
+      Slot slot = slots.get(index);
+      // If the slot cannot be added to, check the next slot.
+      if (slot.isFake() || !slot.mayPlace(itemStack)) {
+        continue;
+      }
+
+      if (slot.hasItem()) {
+        // If the item isn't stackable, check the next slot.
+        if (!stackable) {
+          continue;
+        }
+        // Otherwise, add as many as we can from our stack to the slot.
+        modified |= addToExistingStack(itemStack, slot);
+      } else {
+        // If this is the first empty slot, keep track of it for later use.
+        if (firstEmpty == null) {
+          firstEmpty = slot;
+        }
+        // If the item isn't stackable, we've located the slot we're adding it to, so we're done.
+        if (!stackable) {
+          break;
+        }
+      }
+    }
+
+    // If the item hasn't been fully added yet, add as many as we can to the first open slot.
+    if (!itemStack.isEmpty() && firstEmpty != null) {
+      firstEmpty.setByPlayer(itemStack.split(Math.min(itemStack.getCount(), firstEmpty.getMaxStackSize(itemStack))));
+      firstEmpty.setChanged();
+      modified = true;
+    }
+
+    return modified;
+  }
+
+  private static boolean addToExistingStack(ItemStack itemStack, Slot slot) {
+    ItemStack existing = slot.getItem();
+
+    // If the items aren't the same, we can't add our item.
+    if (!ItemStack.isSameItemSameComponents(itemStack, existing)) {
+      return false;
+    }
+
+    int max = slot.getMaxStackSize(existing);
+    int existingCount = existing.getCount();
+
+    // If the stack is already full, we can't add more.
+    if (existingCount >= max) {
+      return false;
+    }
+
+    int total = existingCount + itemStack.getCount();
+
+    // If the existing item can accept the entirety of our item, we're done!
+    if (total <= max) {
+      itemStack.setCount(0);
+      existing.setCount(total);
+      slot.setChanged();
+      return true;
+    }
+
+    // Otherwise, add as many as we can.
+    itemStack.shrink(max - existingCount);
+    existing.setCount(max);
+    slot.setChanged();
+    return true;
+  }
+
+  @Override
+  public void clicked(int i, int j, @NotNull ClickType clickType, @NotNull Player player) {
+    if (viewOnly) {
+      if (clickType == ClickType.QUICK_CRAFT) {
+        sendAllDataToRemote();
+      }
+      return;
+    }
+    super.clicked(i, j, clickType, player);
+  }
+
+  @Override
+  public boolean stillValid(@NotNull Player player) {
+    return true;
+  }
+
+  // Overrides from here on are purely to modify the sync process to send placeholder items.
+  @Override
+  protected @NotNull Slot addSlot(@NotNull Slot slot) {
+    slot.index = this.slots.size();
+    this.slots.add(slot);
+    this.lastSlots.add(ItemStack.EMPTY);
+    this.remoteSlots.add(ItemStack.EMPTY);
+    return slot;
+  }
+
+  @Override
+  protected @NotNull DataSlot addDataSlot(@NotNull DataSlot dataSlot) {
+    this.dataSlots.add(dataSlot);
+    this.remoteDataSlots.add(0);
+    return dataSlot;
+  }
+
+  @Override
+  protected void addDataSlots(ContainerData containerData) {
+    for (int i = 0; i < containerData.getCount(); i++) {
+      this.addDataSlot(DataSlot.forContainer(containerData, i));
+    }
+  }
+
+  @Override
+  public void addSlotListener(@NotNull ContainerListener containerListener) {
+    if (!this.containerListeners.contains(containerListener)) {
+      this.containerListeners.add(containerListener);
+      this.broadcastChanges();
+    }
+  }
+
+  @Override
+  public void setSynchronizer(@NotNull ContainerSynchronizer containerSynchronizer) {
+    this.synchronizer = containerSynchronizer;
+    this.sendAllDataToRemote();
+  }
+
+  @Override
+  public void sendAllDataToRemote() {
+    for (int index = 0; index < slots.size(); ++index) {
+      Slot slot = slots.get(index);
+      this.remoteSlots.set(index, (slot instanceof SlotPlaceholder placeholder ? placeholder.getOrDefault() : slot.getItem()).copy());
+    }
+
+    remoteCarried = getCarried().copy();
+
+    for (int index = 0; index < this.dataSlots.size(); ++index) {
+      this.remoteDataSlots.set(index, this.dataSlots.get(index).get());
+    }
+
+    if (this.synchronizer != null) {
+      this.synchronizer.sendInitialData(this, this.remoteSlots, this.remoteCarried, this.remoteDataSlots.toIntArray());
+    }
+  }
+
+  @Override
+  public void broadcastCarriedItem() {
+    this.remoteCarried = this.getCarried().copy();
+    if (this.synchronizer != null) {
+      this.synchronizer.sendCarriedChange(this, this.remoteCarried);
+    }
+  }
+
+  @Override
+  public void removeSlotListener(@NotNull ContainerListener containerListener) {
+    this.containerListeners.remove(containerListener);
+  }
+
+  @Override
+  public void broadcastChanges() {
+    for (int index = 0; index < this.slots.size(); ++index) {
+      Slot slot = this.slots.get(index);
+      ItemStack itemstack = slot instanceof SlotPlaceholder placeholder ? placeholder.getOrDefault() : slot.getItem();
+      Supplier<ItemStack> supplier = Suppliers.memoize(itemstack::copy);
+      this.triggerSlotListeners(index, itemstack, supplier);
+      this.synchronizeSlotToRemote(index, itemstack, supplier);
+    }
+
+    this.synchronizeCarriedToRemote();
+
+    for (int index = 0; index < this.dataSlots.size(); ++index) {
+      DataSlot dataSlot = this.dataSlots.get(index);
+      int j = dataSlot.get();
+      if (dataSlot.checkAndClearUpdateFlag()) {
+        this.updateDataSlotListeners(index, j);
+      }
+
+      this.synchronizeDataSlotToRemote(index, j);
+    }
+  }
+
+  @Override
+  public void broadcastFullState() {
+    for (int index = 0; index < this.slots.size(); ++index) {
+      ItemStack itemstack = this.slots.get(index).getItem();
+      this.triggerSlotListeners(index, itemstack, itemstack::copy);
+    }
+
+    for (int index = 0; index < this.dataSlots.size(); ++index) {
+      DataSlot containerproperty = this.dataSlots.get(index);
+      if (containerproperty.checkAndClearUpdateFlag()) {
+        this.updateDataSlotListeners(index, containerproperty.get());
+      }
+    }
+
+    this.sendAllDataToRemote();
+  }
+
+  private void updateDataSlotListeners(int i, int j) {
+    for (ContainerListener containerListener : this.containerListeners) {
+      containerListener.dataChanged(this, i, j);
+    }
+  }
+
+  private void triggerSlotListeners(int index, ItemStack itemStack, Supplier<ItemStack> supplier) {
+    ItemStack itemStack1 = this.lastSlots.get(index);
+    if (!ItemStack.matches(itemStack1, itemStack)) {
+      ItemStack itemStack2 = supplier.get();
+      this.lastSlots.set(index, itemStack2);
+
+      for (ContainerListener containerListener : this.containerListeners) {
+        containerListener.slotChanged(this, index, itemStack2);
+      }
+    }
+  }
+
+  private void synchronizeSlotToRemote(int i, ItemStack itemStack, Supplier<ItemStack> supplier) {
+    if (!this.suppressRemoteUpdates) {
+      ItemStack itemStack1 = this.remoteSlots.get(i);
+      if (!ItemStack.matches(itemStack1, itemStack)) {
+        ItemStack itemstack2 = supplier.get();
+        this.remoteSlots.set(i, itemstack2);
+        if (this.synchronizer != null) {
+          this.synchronizer.sendSlotChange(this, i, itemstack2);
+        }
+      }
+    }
+  }
+
+  private void synchronizeDataSlotToRemote(int index, int value) {
+    if (!this.suppressRemoteUpdates) {
+      int existing = this.remoteDataSlots.getInt(index);
+      if (existing != value) {
+        this.remoteDataSlots.set(index, value);
+        if (this.synchronizer != null) {
+          this.synchronizer.sendDataChange(this, index, value);
+        }
+      }
+    }
+  }
+
+  private void synchronizeCarriedToRemote() {
+    if (!this.suppressRemoteUpdates && !ItemStack.matches(this.getCarried(), this.remoteCarried)) {
+      this.remoteCarried = this.getCarried().copy();
+      if (this.synchronizer != null) {
+        this.synchronizer.sendCarriedChange(this, this.remoteCarried);
+      }
+    }
+  }
+
+  @Override
+  public void setRemoteCarried(ItemStack itemstack) {
+    this.remoteCarried = itemstack.copy();
+  }
+
+  @Override
+  public void suppressRemoteUpdates() {
+    this.suppressRemoteUpdates = true;
+  }
+
+  @Override
+  public void resumeRemoteUpdates() {
+    this.suppressRemoteUpdates = false;
+  }
+
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/container/menu/OpenEnderChestMenu.java

@@ -0,0 +1,60 @@
+package com.lishid.openinv.internal.paper1_21_4.container.menu;
+
+import com.lishid.openinv.internal.common.container.OpenEnderChest;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+public class OpenEnderChestMenu extends OpenChestMenu<OpenEnderChest> {
+
+  public OpenEnderChestMenu(
+      @NotNull OpenEnderChest enderChest,
+      @NotNull ServerPlayer viewer,
+      int containerId,
+      boolean viewOnly
+  ) {
+    super(
+        com.lishid.openinv.internal.common.container.menu.OpenChestMenu.getChestMenuType(enderChest.getContainerSize()),
+        containerId,
+        enderChest,
+        viewer,
+        viewOnly
+    );
+  }
+
+  @Override
+  public @NotNull ItemStack quickMoveStack(@NotNull Player player, int index) {
+    if (viewOnly) {
+      return ItemStack.EMPTY;
+    }
+
+    // See ChestMenu
+    Slot slot = this.slots.get(index);
+
+    if (slot.isFake() || !slot.hasItem()) {
+      return ItemStack.EMPTY;
+    }
+
+    ItemStack itemStack = slot.getItem();
+    ItemStack original = itemStack.copy();
+
+    if (index < topSize) {
+      if (!this.moveItemStackTo(itemStack, topSize, this.slots.size(), true)) {
+        return ItemStack.EMPTY;
+      }
+    } else if (!this.moveItemStackTo(itemStack, 0, topSize, false)) {
+      return ItemStack.EMPTY;
+    }
+
+    if (itemStack.isEmpty()) {
+      slot.setByPlayer(ItemStack.EMPTY);
+    } else {
+      slot.setChanged();
+    }
+
+    return original;
+  }
+
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/container/menu/OpenInventoryMenu.java

@@ -0,0 +1,265 @@
+package com.lishid.openinv.internal.paper1_21_4.container.menu;
+
+import com.google.common.base.Preconditions;
+import com.lishid.openinv.internal.common.container.bukkit.OpenDummyPlayerInventory;
+import com.lishid.openinv.internal.common.container.slot.ContentDrop;
+import com.lishid.openinv.internal.common.container.slot.SlotViewOnly;
+import com.lishid.openinv.internal.paper1_21_4.container.OpenInventory;
+import com.lishid.openinv.internal.paper1_21_4.container.bukkit.OpenPlayerInventorySelf;
+import com.lishid.openinv.internal.paper1_21_4.container.slot.ContentEquipment;
+import com.lishid.openinv.util.Permissions;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.ChestMenu;
+import net.minecraft.world.inventory.MenuType;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.craftbukkit.inventory.CraftInventoryView;
+import org.bukkit.craftbukkit.inventory.CraftItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.Inventory;
+import org.bukkit.inventory.InventoryView;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class OpenInventoryMenu extends OpenChestMenu<OpenInventory> {
+
+  private int offset;
+
+  public OpenInventoryMenu(OpenInventory inventory, ServerPlayer viewer, int i, boolean viewOnly) {
+    super(getMenuType(inventory, viewer), i, inventory, viewer, viewOnly);
+  }
+
+  private static MenuType<ChestMenu> getMenuType(OpenInventory inventory, ServerPlayer viewer) {
+    int size = inventory.getContainerSize();
+    // Disallow duplicate access to own main inventory contents.
+    if (inventory.getOwnerHandle().equals(viewer)) {
+      size -= viewer.getInventory().items.size();
+      size = ((int) Math.ceil(size / 9.0)) * 9;
+    }
+
+    return com.lishid.openinv.internal.common.container.menu.OpenChestMenu.getChestMenuType(size);
+  }
+
+  @Override
+  protected void preSlotSetup() {
+    offset = ownContainer ? viewer.getInventory().items.size() : 0;
+  }
+
+  @Override
+  protected @NotNull Slot getUpperSlot(int index, int x, int y) {
+    index += offset;
+    Slot slot = container.getMenuSlot(index, x, y);
+
+    // If the slot cannot be interacted with there's nothing to configure.
+    if (slot.getClass().equals(SlotViewOnly.class)) {
+      return slot;
+    }
+
+    // Remove drop slot if viewer is not allowed to use it.
+    if (slot instanceof ContentDrop.SlotDrop
+        && (viewOnly || !Permissions.INVENTORY_SLOT_DROP.hasPermission(viewer.getBukkitEntity()))) {
+      return new SlotViewOnly(container, index, x, y);
+    }
+
+    if (slot instanceof ContentEquipment.SlotEquipment equipment) {
+      if (viewOnly) {
+        return SlotViewOnly.wrap(slot);
+      }
+
+      Permissions perm = switch (equipment.getEquipmentSlot()) {
+        case HEAD -> Permissions.INVENTORY_SLOT_HEAD_ANY;
+        case CHEST -> Permissions.INVENTORY_SLOT_CHEST_ANY;
+        case LEGS -> Permissions.INVENTORY_SLOT_LEGS_ANY;
+        case FEET -> Permissions.INVENTORY_SLOT_FEET_ANY;
+        // Off-hand can hold anything, not just equipment.
+        default -> null;
+      };
+
+      // If the viewer doesn't have permission, only allow equipment the viewee can equip in the slot.
+      if (perm != null && !perm.hasPermission(viewer.getBukkitEntity())) {
+        equipment.onlyEquipmentFor(container.getOwnerHandle());
+      }
+
+      // Equipment slots are a core part of the inventory, so they will always be shown.
+      return slot;
+    }
+
+    // When viewing own inventory, only allow access to equipment and drop slots (equipment allowed above).
+    if (ownContainer && !(slot instanceof ContentDrop.SlotDrop)) {
+      return new SlotViewOnly(container, index, x, y);
+    }
+
+    if (viewOnly) {
+      return SlotViewOnly.wrap(slot);
+    }
+
+    return slot;
+  }
+
+  @Override
+  protected @NotNull CraftInventoryView<OpenChestMenu<OpenInventory>, Inventory> createBukkitEntity() {
+    org.bukkit.inventory.Inventory bukkitInventory;
+    if (viewOnly) {
+      bukkitInventory = new OpenDummyPlayerInventory(container);
+    } else if (ownContainer) {
+      bukkitInventory = new OpenPlayerInventorySelf(container, offset);
+    } else {
+      bukkitInventory = container.getBukkitInventory();
+    }
+
+    return new CraftInventoryView<>(viewer.getBukkitEntity(), bukkitInventory, this) {
+      @Override
+      public org.bukkit.inventory.ItemStack getItem(int index) {
+        if (viewOnly || index < 0) {
+          return null;
+        }
+
+        Slot slot = slots.get(index);
+        return CraftItemStack.asCraftMirror(slot.hasItem() ? slot.getItem() : ItemStack.EMPTY);
+      }
+
+      @Override
+      public boolean isInTop(int rawSlot) {
+        return rawSlot < topSize;
+      }
+
+      @Override
+      public @Nullable Inventory getInventory(int rawSlot) {
+        if (viewOnly) {
+          return null;
+        }
+        if (rawSlot == InventoryView.OUTSIDE || rawSlot == -1) {
+          return null;
+        }
+        Preconditions.checkArgument(
+            rawSlot >= 0 && rawSlot < topSize + offset + BOTTOM_INVENTORY_SIZE,
+            "Slot %s outside of inventory",
+            rawSlot
+        );
+        if (rawSlot > topSize) {
+          return getBottomInventory();
+        }
+        Slot slot = slots.get(rawSlot);
+        if (slot.isFake()) {
+          return null;
+        }
+        return getTopInventory();
+      }
+
+      @Override
+      public int convertSlot(int rawSlot) {
+        if (viewOnly) {
+          return InventoryView.OUTSIDE;
+        }
+        if (rawSlot < 0) {
+          return rawSlot;
+        }
+        if (rawSlot < topSize) {
+          Slot slot = slots.get(rawSlot);
+          if (slot.isFake()) {
+            return InventoryView.OUTSIDE;
+          }
+          return rawSlot;
+        }
+
+        int slot = rawSlot - topSize;
+
+        if (slot >= 27) {
+          slot -= 27;
+        } else {
+          slot += 9;
+        }
+
+        return slot;
+      }
+
+      @Override
+      public @NotNull InventoryType.SlotType getSlotType(int slot) {
+        if (viewOnly || slot < 0) {
+          return InventoryType.SlotType.OUTSIDE;
+        }
+        if (slot >= topSize) {
+          slot -= topSize;
+          if (slot >= 27) {
+            return InventoryType.SlotType.QUICKBAR;
+          }
+          return InventoryType.SlotType.CONTAINER;
+        }
+        return OpenInventoryMenu.this.container.getSlotType(offset + slot);
+      }
+
+      @Override
+      public int countSlots() {
+        return topSize + BOTTOM_INVENTORY_SIZE;
+      }
+    };
+  }
+
+  @Override
+  public @NotNull ItemStack quickMoveStack(@NotNull Player player, int index) {
+    if (viewOnly) {
+      return ItemStack.EMPTY;
+    }
+
+    // See ChestMenu and InventoryMenu
+    Slot slot = this.slots.get(index);
+
+    if (!slot.hasItem() || slot.isFake()) {
+      return ItemStack.EMPTY;
+    }
+
+    ItemStack itemStack = slot.getItem();
+    ItemStack originalStack = itemStack.copy();
+
+    if (index < topSize) {
+      // If we're moving top to bottom, do a normal transfer.
+      if (!this.moveItemStackTo(itemStack, topSize, this.slots.size(), true)) {
+        return ItemStack.EMPTY;
+      }
+    } else {
+      EquipmentSlot equipmentSlot = player.getEquipmentSlotForItem(itemStack);
+      boolean movedGear = switch (equipmentSlot) {
+        // If this is gear, try to move it to the correct slot first.
+        case OFFHAND, FEET, LEGS, CHEST, HEAD -> {
+          // Locate the correct slot in the contents following the main inventory.
+          for (int extra = container.getOwnerHandle().getInventory().items.size() - offset; extra < topSize; ++extra) {
+            Slot extraSlot = getSlot(extra);
+            if (extraSlot instanceof ContentEquipment.SlotEquipment equipSlot
+                && equipSlot.getEquipmentSlot() == equipmentSlot) {
+              // If we've found a matching slot, try to move to it.
+              // If this succeeds, even partially, we will not attempt to move to other slots.
+              // Otherwise, armor is already occupied, so we'll fall through to main inventory.
+              yield this.moveItemStackTo(itemStack, extra, extra + 1, false);
+            }
+          }
+          yield false;
+        }
+        // Non-gear gets no special treatment.
+        default -> false;
+      };
+
+      // If main inventory is not available, there's nowhere else to move.
+      if (offset != 0) {
+        if (!movedGear) {
+          return ItemStack.EMPTY;
+        }
+      } else {
+        // If we didn't move to a gear slot, try to move to a main inventory slot.
+        if (!movedGear && !this.moveItemStackTo(itemStack, 0, container.getOwnerHandle().getInventory().items.size(), true)) {
+          return ItemStack.EMPTY;
+        }
+      }
+    }
+
+    if (itemStack.isEmpty()) {
+      slot.setByPlayer(ItemStack.EMPTY);
+    } else {
+      slot.setChanged();
+    }
+
+    return originalStack;
+  }
+
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/container/slot/ContentEquipment.java

@@ -0,0 +1,80 @@
+package com.lishid.openinv.internal.paper1_21_4.container.slot;
+
+import com.lishid.openinv.internal.common.container.slot.ContentList;
+import com.lishid.openinv.internal.common.container.slot.SlotPlaceholder;
+import com.lishid.openinv.internal.common.container.slot.placeholder.Placeholders;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A slot for equipment that displays placeholders if empty.
+ */
+public class ContentEquipment extends ContentList {
+
+  private final ItemStack placeholder;
+  private final EquipmentSlot equipmentSlot;
+
+  public ContentEquipment(ServerPlayer holder, int index, EquipmentSlot equipmentSlot) {
+    super(holder, index, InventoryType.SlotType.ARMOR);
+    placeholder = switch (equipmentSlot) {
+      case HEAD -> Placeholders.emptyHelmet;
+      case CHEST -> Placeholders.emptyChestplate;
+      case LEGS -> Placeholders.emptyLeggings;
+      case FEET -> Placeholders.emptyBoots;
+      default -> Placeholders.emptyOffHand;
+    };
+    this.equipmentSlot = equipmentSlot;
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.items = holder.getInventory().armor;
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotEquipment(container, slot, x, y);
+  }
+
+  public class SlotEquipment extends SlotPlaceholder {
+
+    private ServerPlayer viewer;
+
+    SlotEquipment(Container container, int index, int x, int y) {
+      super(container, index, x, y);
+    }
+
+    @Override
+    public ItemStack getOrDefault() {
+      ItemStack itemStack = getItem();
+      if (!itemStack.isEmpty()) {
+        return itemStack;
+      }
+      return placeholder;
+    }
+
+    public EquipmentSlot getEquipmentSlot() {
+      return equipmentSlot;
+    }
+
+    public void onlyEquipmentFor(ServerPlayer viewer) {
+      this.viewer = viewer;
+    }
+
+    @Override
+    public boolean mayPlace(@NotNull ItemStack itemStack) {
+      if (viewer == null) {
+        return true;
+      }
+
+      return equipmentSlot == EquipmentSlot.OFFHAND || viewer.getEquipmentSlotForItem(itemStack) == equipmentSlot;
+    }
+
+  }
+
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/container/slot/ContentOffHand.java

@@ -0,0 +1,53 @@
+package com.lishid.openinv.internal.paper1_21_4.container.slot;
+
+import com.lishid.openinv.internal.common.player.BaseOpenPlayer;
+import net.minecraft.network.protocol.game.ClientboundContainerSetSlotPacket;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.inventory.InventoryMenu;
+import net.minecraft.world.inventory.Slot;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A slot for equipment that updates held items if necessary.
+ */
+public class ContentOffHand extends ContentEquipment {
+
+  private ServerPlayer holder;
+
+  public ContentOffHand(ServerPlayer holder, int localIndex) {
+    super(holder, localIndex, EquipmentSlot.OFFHAND);
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.items = holder.getInventory().offhand;
+    this.holder = holder;
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return InventoryType.SlotType.QUICKBAR;
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotEquipment(container, slot, x, y) {
+      @Override
+      public void setChanged() {
+        if (BaseOpenPlayer.isConnected(holder.connection) && holder.containerMenu != holder.inventoryMenu) {
+          holder.connection.send(
+              new ClientboundContainerSetSlotPacket(
+                  holder.inventoryMenu.containerId,
+                  holder.inventoryMenu.incrementStateId(),
+                  InventoryMenu.SHIELD_SLOT,
+                  holder.getOffhandItem()
+              ));
+        }
+      }
+    };
+  }
+
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/container/slot/placeholder/CustomModelBase.java

@@ -0,0 +1,41 @@
+package com.lishid.openinv.internal.paper1_21_4.container.slot.placeholder;
+
+import com.lishid.openinv.internal.common.container.slot.placeholder.PlaceholderLoaderBase;
+import net.minecraft.core.component.DataComponents;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.TagParser;
+import net.minecraft.util.Unit;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.component.CustomModelData;
+import net.minecraft.world.item.component.DyedItemColor;
+import org.jetbrains.annotations.NotNull;
+
+public class CustomModelBase extends PlaceholderLoaderBase {
+
+  private final @NotNull CustomModelData defaultCustomModelData;
+
+  public CustomModelBase(@NotNull CustomModelData defaultCustomModelData) {
+    this.defaultCustomModelData = defaultCustomModelData;
+  }
+
+  @Override
+  protected @NotNull CompoundTag parseTag(@NotNull String itemText) throws Exception {
+    return TagParser.parseTag(itemText);
+  }
+
+  @Override
+  protected void addModelData(@NotNull ItemStack itemStack) {
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, defaultCustomModelData);
+  }
+
+  @Override
+  protected void hideTooltip(@NotNull ItemStack itemStack) {
+    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+  }
+
+  @Override
+  protected DyedItemColor getDye(int rgb) {
+    return new DyedItemColor(rgb, false);
+  }
+
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/container/slot/placeholder/CustomModelPlaceholderLoader.java

@@ -0,0 +1,13 @@
+package com.lishid.openinv.internal.paper1_21_4.container.slot.placeholder;
+
+import net.minecraft.world.item.component.CustomModelData;
+
+import java.util.List;
+
+public class CustomModelPlaceholderLoader extends CustomModelBase {
+
+  public CustomModelPlaceholderLoader() {
+    super(new CustomModelData(List.of(), List.of(), List.of("openinv:custom"), List.of()));
+  }
+
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/player/OpenPlayer.java

@@ -0,0 +1,36 @@
+package com.lishid.openinv.internal.paper1_21_4.player;
+
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.server.level.ServerPlayer;
+import org.bukkit.craftbukkit.CraftServer;
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class OpenPlayer extends com.lishid.openinv.internal.paper1_21_5.player.OpenPlayer {
+
+  protected OpenPlayer(
+      CraftServer server, ServerPlayer entity,
+      PlayerManager manager
+  ) {
+    super(server, entity, manager);
+  }
+
+  @Contract("null -> new")
+  @Override
+  protected @NotNull CompoundTag getWritableTag(@Nullable CompoundTag oldData) {
+    if (oldData == null) {
+      return new CompoundTag();
+    }
+
+    // Copy old data. This is a deep clone, so operating on it should be safe.
+    oldData = oldData.copy();
+
+    // Remove vanilla/server data that is not written every time.
+    oldData.getAllKeys()
+        .removeIf(key -> RESET_TAGS.contains(key) || key.startsWith("Bukkit"));
+
+    return oldData;
+  }
+
+}

internal/paper1_21_4/src/main/java/com/lishid/openinv/internal/paper1_21_4/player/PlayerManager.java

@@ -0,0 +1,73 @@
+package com.lishid.openinv.internal.paper1_21_4.player;
+
+import com.mojang.serialization.Dynamic;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtOps;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.dimension.DimensionType;
+import org.bukkit.Bukkit;
+import org.bukkit.World;
+import org.bukkit.craftbukkit.CraftWorld;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.UUID;
+import java.util.logging.Logger;
+
+public class PlayerManager extends com.lishid.openinv.internal.paper1_21_5.player.PlayerManager {
+
+  public PlayerManager(@NotNull Logger logger) {
+    super(logger);
+  }
+
+  @Override
+  protected void parseWorld(@NotNull ServerPlayer player, @NotNull CompoundTag loadedData) {
+    // See PlayerList#placeNewPlayer
+    World bukkitWorld;
+    if (loadedData.contains("WorldUUIDMost") && loadedData.contains("WorldUUIDLeast")) {
+      // Modern Bukkit world.
+      bukkitWorld = Bukkit.getServer().getWorld(new UUID(loadedData.getLong("WorldUUIDMost"), loadedData.getLong("WorldUUIDLeast")));
+    } else if (loadedData.contains("world", net.minecraft.nbt.Tag.TAG_STRING)) {
+      // Legacy Bukkit world.
+      bukkitWorld = Bukkit.getServer().getWorld(loadedData.getString("world"));
+    } else {
+      // Vanilla player data.
+      DimensionType.parseLegacy(new Dynamic<>(NbtOps.INSTANCE, loadedData.get("Dimension")))
+          .resultOrPartial(logger::warning)
+          .map(player.server::getLevel)
+          // If ServerLevel exists, set, otherwise move to spawn.
+          .ifPresentOrElse(player::setServerLevel, () -> spawnInDefaultWorld(player.server, player));
+      return;
+    }
+    if (bukkitWorld == null) {
+      spawnInDefaultWorld(player.server, player);
+      return;
+    }
+    player.setServerLevel(((CraftWorld) bukkitWorld).getHandle());
+  }
+
+  @Override
+  protected void spawnInDefaultWorld(@NotNull MinecraftServer server, @NotNull ServerPlayer player) {
+    ServerLevel level = server.getLevel(Level.OVERWORLD);
+    if (level != null) {
+      // Adjust player to default spawn (in keeping with Paper handling) when world not found.
+      player.moveTo(player.adjustSpawnLocation(level, level.getSharedSpawnPos()).getBottomCenter(), level.getSharedSpawnAngle(), 0.0F);
+      player.spawnIn(level);
+    } else {
+      logger.warning("Tried to load player with invalid world when no fallback was available!");
+    }
+  }
+
+  @Override
+  protected void injectPlayer(@NotNull MinecraftServer server, @NotNull ServerPlayer player) throws IllegalAccessException {
+    if (bukkitEntity == null) {
+      return;
+    }
+
+    bukkitEntity.setAccessible(true);
+    bukkitEntity.set(player, new OpenPlayer(player.server.server, player, this));
+  }
+
+}

internal/paper1_21_5/build.gradle.kts

@@ -0,0 +1,26 @@
+plugins {
+  `openinv-base`
+  alias(libs.plugins.paperweight)
+}
+
+configurations.all {
+  resolutionStrategy.capabilitiesResolution.withCapability("org.spigotmc:spigot-api") {
+    val paper = candidates.firstOrNull {
+      it.id.let { id ->
+        id is ModuleComponentIdentifier && id.module == "paper-api"
+      }
+    }
+    if (paper != null) {
+      select(paper)
+    }
+    because("module is written for Paper servers")
+  }
+}
+
+dependencies {
+  implementation(project(":openinvapi"))
+  implementation(project(":openinvcommon"))
+  implementation(project(":openinvadaptercommon"))
+
+  paperweight.paperDevBundle("1.21.5-R0.1-SNAPSHOT")
+}

internal/paper1_21_5/src/main/java/com/lishid/openinv/internal/paper1_21_5/InternalAccessor.java

@@ -0,0 +1,37 @@
+package com.lishid.openinv.internal.paper1_21_5;
+
+import com.lishid.openinv.internal.paper1_21_5.container.slot.placeholder.PlaceholderLoaderLegacyParse;
+import com.lishid.openinv.internal.paper1_21_5.player.PlayerManager;
+import com.lishid.openinv.util.lang.LanguageManager;
+import org.bukkit.configuration.ConfigurationSection;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class InternalAccessor extends com.lishid.openinv.internal.common.InternalAccessor {
+
+  private final @NotNull PlayerManager manager;
+
+  public InternalAccessor(@NotNull Logger logger, @NotNull LanguageManager lang) {
+    super(logger, lang);
+    manager = new PlayerManager(logger);
+  }
+
+  @Override
+  public @NotNull PlayerManager getPlayerManager() {
+    return manager;
+  }
+
+  @Override
+  public void reload(@NotNull ConfigurationSection config) {
+    ConfigurationSection placeholders = config.getConfigurationSection("placeholders");
+    try {
+      // Reset placeholders to defaults and try to load configuration.
+      new PlaceholderLoaderLegacyParse().load(placeholders);
+    } catch (Exception e) {
+      logger.log(Level.WARNING, "Caught exception loading placeholder overrides!", e);
+    }
+  }
+
+}

internal/paper1_21_5/src/main/java/com/lishid/openinv/internal/paper1_21_5/container/slot/placeholder/PlaceholderLoaderLegacyParse.java

@@ -0,0 +1,36 @@
+package com.lishid.openinv.internal.paper1_21_5.container.slot.placeholder;
+
+import com.lishid.openinv.internal.common.container.slot.placeholder.PlaceholderLoader;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.configuration.ConfigurationSection;
+import org.bukkit.craftbukkit.CraftRegistry;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Optional;
+
+public class PlaceholderLoaderLegacyParse extends PlaceholderLoader {
+
+  @Override
+  protected @NotNull ItemStack parse(
+      @Nullable ConfigurationSection section,
+      @NotNull String path,
+      @NotNull ItemStack defaultStack
+  ) throws Exception {
+    if (section == null) {
+      return defaultStack;
+    }
+
+    String itemText = section.getString(path);
+
+    if (itemText == null) {
+      return defaultStack;
+    }
+
+    CompoundTag compoundTag = parseTag(itemText);
+    Optional<ItemStack> parsed = ItemStack.parse(CraftRegistry.getMinecraftRegistry(), compoundTag);
+    return parsed.filter(itemStack -> !itemStack.isEmpty()).orElse(defaultStack);
+  }
+
+}

internal/paper1_21_5/src/main/java/com/lishid/openinv/internal/paper1_21_5/player/OpenPlayer.java

@@ -0,0 +1,54 @@
+package com.lishid.openinv.internal.paper1_21_5.player;
+
+import com.lishid.openinv.event.OpenEvents;
+import com.lishid.openinv.internal.common.player.BaseOpenPlayer;
+import com.mojang.logging.LogUtils;
+import net.minecraft.Util;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtIo;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.level.storage.PlayerDataStorage;
+import org.bukkit.craftbukkit.CraftServer;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+public class OpenPlayer extends BaseOpenPlayer {
+
+  protected OpenPlayer(CraftServer server, ServerPlayer entity, PlayerManager manager) {
+    super(server, entity, manager);
+  }
+
+  @Override
+  public void saveData() {
+    if (OpenEvents.saveCancelled(this)) {
+      return;
+    }
+
+    ServerPlayer player = this.getHandle();
+    // See net.minecraft.world.level.storage.PlayerDataStorage#save(EntityHuman)
+    try {
+      PlayerDataStorage worldNBTStorage = player.server.getPlayerList().playerIo;
+
+      CompoundTag oldData = isOnline() ? null : worldNBTStorage.load(player.getName().getString(), player.getStringUUID()).orElse(null);
+      CompoundTag playerData = getWritableTag(oldData);
+
+      playerData = player.saveWithoutId(playerData);
+
+      if (oldData != null) {
+        // Revert certain special data values when offline.
+        revertSpecialValues(playerData, oldData);
+      }
+
+      Path playerDataDir = worldNBTStorage.getPlayerDir().toPath();
+      Path tempFile = Files.createTempFile(playerDataDir, player.getStringUUID() + "-", ".dat");
+      NbtIo.writeCompressed(playerData, tempFile);
+      Path dataFile = playerDataDir.resolve(player.getStringUUID() + ".dat");
+      Path backupFile = playerDataDir.resolve(player.getStringUUID() + ".dat_old");
+      Util.safeReplaceFile(dataFile, tempFile, backupFile);
+    } catch (Exception e) {
+      LogUtils.getLogger().warn("Failed to save player data for {}: {}", player.getScoreboardName(), e);
+    }
+  }
+
+}

internal/paper1_21_5/src/main/java/com/lishid/openinv/internal/paper1_21_5/player/PlayerManager.java

@@ -0,0 +1,106 @@
+package com.lishid.openinv.internal.paper1_21_5.player;
+
+import com.mojang.serialization.Dynamic;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtOps;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.level.dimension.DimensionType;
+import org.bukkit.Bukkit;
+import org.bukkit.World;
+import org.bukkit.craftbukkit.CraftWorld;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Optional;
+import java.util.UUID;
+import java.util.logging.Logger;
+
+public class PlayerManager extends com.lishid.openinv.internal.common.player.PlayerManager {
+
+  public PlayerManager(@NotNull Logger logger) {
+    super(logger);
+  }
+
+  @Override
+  protected boolean loadData(@NotNull MinecraftServer server, @NotNull ServerPlayer player) {
+    // See CraftPlayer#loadData
+    CompoundTag loadedData = server.getPlayerList().playerIo.load(player).orElse(null);
+
+    if (loadedData == null) {
+      // Exceptions with loading are logged.
+      return false;
+    }
+
+    // Read basic data into the player.
+    player.load(loadedData);
+    // Game type settings are also loaded separately.
+    player.loadGameTypes(loadedData);
+
+    // World is not loaded by ServerPlayer#load(CompoundTag) on Paper.
+    parseWorld(player, loadedData);
+
+    return true;
+  }
+
+  protected void parseWorld(@NotNull ServerPlayer player, @NotNull CompoundTag loadedData) {
+    // See PlayerList#placeNewPlayer
+    World bukkitWorld;
+    Optional<Long> msbs = loadedData.getLong("WorldUUIDMost");
+    Optional<Long> lsbs = loadedData.getLong("WorldUUIDLeast");
+    if (msbs.isPresent() && lsbs.isPresent()) {
+      // Modern Bukkit world.
+      bukkitWorld = Bukkit.getServer().getWorld(new UUID(msbs.get(), lsbs.get()));
+    } else {
+      Optional<String> worldName = loadedData.getString("world");
+      if (worldName.isPresent()) {
+        // Legacy Bukkit world.
+        bukkitWorld = Bukkit.getServer().getWorld(worldName.get());
+      } else {
+        // Vanilla player data.
+        DimensionType.parseLegacy(new Dynamic<>(NbtOps.INSTANCE, loadedData.get("Dimension")))
+            .resultOrPartial(logger::warning)
+            .map(player.server::getLevel)
+            // If ServerLevel exists, set, otherwise move to spawn.
+            .ifPresentOrElse(player::setServerLevel, () -> spawnInDefaultWorld(player.server, player));
+        return;
+      }
+    }
+    if (bukkitWorld == null) {
+      spawnInDefaultWorld(player.server, player);
+      return;
+    }
+    player.setServerLevel(((CraftWorld) bukkitWorld).getHandle());
+  }
+
+  @Override
+  public @NotNull Player inject(@NotNull Player player) {
+    try {
+      ServerPlayer nmsPlayer = getHandle(player);
+      if (nmsPlayer.getBukkitEntity() instanceof OpenPlayer openPlayer) {
+        return openPlayer;
+      }
+      injectPlayer(nmsPlayer.server, nmsPlayer);
+      return nmsPlayer.getBukkitEntity();
+    } catch (IllegalAccessException e) {
+      logger.log(
+          java.util.logging.Level.WARNING,
+          e,
+          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!"
+      );
+      return player;
+    }
+  }
+
+  @Override
+  protected void injectPlayer(@NotNull MinecraftServer server, @NotNull ServerPlayer player) throws IllegalAccessException {
+    if (bukkitEntity == null) {
+      return;
+    }
+
+    bukkitEntity.setAccessible(true);
+
+    bukkitEntity.set(player, new OpenPlayer(player.server.server, player, this));
+  }
+
+}

internal/spigot/build.gradle.kts

@@ -1,21 +1,24 @@
+import com.github.jikoo.openinv.SpigotDependencyExtension
+import com.github.jikoo.openinv.SpigotReobf
+import com.github.jikoo.openinv.SpigotSetup
+
 plugins {
-  `remap-spigot`
   `openinv-base`
   alias(libs.plugins.shadow)
 }
 
-repositories {
-  mavenLocal()
-}
+apply<SpigotSetup>()
+apply<SpigotReobf>()
 
-val spigotVer = "1.21.4-R0.1-SNAPSHOT"
-rootProject.extra["craftbukkitPackage"] = "v1_21_R3"
+val spigotVer = "1.21.8-R0.1-SNAPSHOT"
+// Used by common adapter to relocate Craftbukkit classes to a versioned package.
+rootProject.extra["craftbukkitPackage"] = "v1_21_R5"
 
 configurations.all {
   resolutionStrategy.capabilitiesResolution.withCapability("org.spigotmc:spigot-api") {
     val spigot = candidates.firstOrNull {
-      it.id.let {
-        id -> id is ModuleComponentIdentifier && id.module == "spigot-api"
+      it.id.let { id ->
+        id is ModuleComponentIdentifier && id.module == "spigot-api"
       }
     }
     if (spigot != null) {
@@ -27,7 +30,7 @@ configurations.all {
 
 dependencies {
   compileOnly(libs.spigotapi)
-  compileOnly(create("org.spigotmc", "spigot", spigotVer, classifier = "remapped-mojang"))
+  extensions.getByType(SpigotDependencyExtension::class.java).version = spigotVer
 
   compileOnly(project(":openinvapi"))
   compileOnly(project(":openinvcommon"))
@@ -39,12 +42,3 @@ dependencies {
 tasks.shadowJar {
   relocate("com.lishid.openinv.internal.common", "com.lishid.openinv.internal.reobf")
 }
-
-// TODO this appears to be a deprecated way to do things
-//   may want to just move all helper methods here.
-tasks.register<Remap_spigot_gradle.RemapTask>("reobf") {
-  notCompatibleWithConfigurationCache("gradle is hard")
-  dependsOn(tasks.shadowJar)
-  inputs.files(tasks.shadowJar.get().outputs.files.files)
-  spigotVersion = spigotVer
-}

internal/spigot/src/main/java/com/lishid/openinv/internal/reobf/container/AnySilentContainer.java

@@ -45,10 +45,10 @@ public class AnySilentContainer extends AnySilentContainerBase {
     this.lang = lang;
     try {
       try {
-        this.serverPlayerGameModeGameType = ServerPlayerGameMode.class.getDeclaredField("b");
+        this.serverPlayerGameModeGameType = ServerPlayerGameMode.class.getDeclaredField("gameModeForPlayer");
         this.serverPlayerGameModeGameType.setAccessible(true);
       } catch (NoSuchFieldException e) {
-        logger.warning("The mapping of ServerPlayerGameMode#gameModeForPlayer has changed!");
+        logger.warning("The field ServerPlayerGameMode#gameModeForPlayer is no longer present!");
         logger.warning("Please report this at https://github.com/Jikoo/OpenInv/issues");
         logger.warning("Attempting to fall through using reflection. Please verify that SilentContainer does not fail.");
         // N.B. gameModeForPlayer is (for now) declared before previousGameModeForPlayer so silent shouldn't break.
@@ -64,7 +64,8 @@ public class AnySilentContainer extends AnySilentContainerBase {
   public boolean activateContainer(
       @NotNull final Player bukkitPlayer,
       final boolean silentchest,
-      @NotNull final org.bukkit.block.Block bukkitBlock) {
+      @NotNull final org.bukkit.block.Block bukkitBlock
+  ) {
 
     // Silent ender chest is API-only
     if (silentchest && bukkitBlock.getType() == Material.ENDER_CHEST) {
@@ -87,11 +88,16 @@ public class AnySilentContainer extends AnySilentContainerBase {
       // Anychest ender chest. See net.minecraft.world.level.block.EnderChestBlock
       PlayerEnderChestContainer enderChest = player.getEnderChestInventory();
       enderChest.setActiveChest(enderChestTile);
-      player.openMenu(new SimpleMenuProvider((containerCounter, playerInventory, ignored) -> {
-        MenuType<?> containers = OpenChestMenu.getChestMenuType(enderChest.getContainerSize());
-        int rows = enderChest.getContainerSize() / 9;
-        return new ChestMenu(containers, containerCounter, playerInventory, enderChest, rows);
-      }, Component.translatable("container.enderchest")));
+      player.openMenu(
+          new SimpleMenuProvider(
+              (containerCounter, playerInventory, ignored) -> {
+                MenuType<?> containers = OpenChestMenu.getChestMenuType(enderChest.getContainerSize());
+                int rows = enderChest.getContainerSize() / 9;
+                return new ChestMenu(containers, containerCounter, playerInventory, enderChest, rows);
+              },
+              Component.translatable("container.enderchest")
+          )
+      );
       bukkitPlayer.incrementStatistic(Statistic.ENDERCHEST_OPENED);
       return true;
     }

internal/spigot/src/main/java/com/lishid/openinv/internal/reobf/container/bukkit/OpenPlayerInventory.java

@@ -0,0 +1,190 @@
+package com.lishid.openinv.internal.reobf.container.bukkit;
+
+import com.google.common.base.Preconditions;
+import com.lishid.openinv.internal.reobf.container.OpenInventory;
+import net.minecraft.core.NonNullList;
+import net.minecraft.world.entity.player.Inventory;
+import org.bukkit.craftbukkit.v1_21_R5.inventory.CraftInventory;
+import org.bukkit.craftbukkit.v1_21_R5.inventory.CraftItemStack;
+import org.bukkit.entity.Player;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.PlayerInventory;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class OpenPlayerInventory extends CraftInventory implements PlayerInventory {
+
+  public OpenPlayerInventory(@NotNull OpenInventory inventory) {
+    super(inventory);
+  }
+
+  @Override
+  public @NotNull OpenInventory getInventory() {
+    return (OpenInventory) super.getInventory();
+  }
+
+  @Override
+  public ItemStack @NotNull [] getContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().getContents());
+  }
+
+  @Override
+  public void setContents(ItemStack[] items) {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    int size = internal.getContainerSize();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+
+    for (int index = 0; index < size; ++index) {
+      if (index < items.length) {
+        internal.setItem(index, CraftItemStack.asNMSCopy(items[index]));
+      } else {
+        internal.setItem(index, net.minecraft.world.item.ItemStack.EMPTY);
+      }
+    }
+  }
+
+  @Override
+  public ItemStack @NotNull [] getStorageContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().getNonEquipmentItems());
+  }
+
+  @Override
+  public void setStorageContents(ItemStack[] items) throws IllegalArgumentException {
+    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().getNonEquipmentItems();
+    int size = list.size();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+    for (int index = 0; index < items.length; ++index) {
+      list.set(index, CraftItemStack.asNMSCopy(items[index]));
+    }
+  }
+
+  @Override
+  public @NotNull InventoryType getType() {
+    return InventoryType.PLAYER;
+  }
+
+  @Override
+  public @NotNull Player getHolder() {
+    return getInventory().getOwner();
+  }
+
+  @Override
+  public @NotNull ItemStack @NotNull [] getArmorContents() {
+    return getInventory().getOwnerHandle().getBukkitEntity().getInventory().getArmorContents();
+  }
+
+  @Override
+  public void setArmorContents(ItemStack @NotNull [] items) {
+    getInventory().getOwnerHandle().getBukkitEntity().getInventory().setArmorContents(items);
+  }
+
+  @Override
+  public @NotNull ItemStack @NotNull [] getExtraContents() {
+    return getInventory().getOwnerHandle().getBukkitEntity().getInventory().getExtraContents();
+  }
+
+  @Override
+  public void setExtraContents(ItemStack @NotNull [] items) {
+    getInventory().getOwnerHandle().getBukkitEntity().getInventory().setExtraContents(items);
+  }
+
+  @Override
+  public @Nullable ItemStack getHelmet() {
+    return getInventory().getOwnerHandle().getBukkitEntity().getInventory().getHelmet();
+  }
+
+  @Override
+  public void setHelmet(@Nullable ItemStack helmet) {
+    getInventory().getOwnerHandle().getBukkitEntity().getInventory().setHelmet(helmet);
+  }
+
+  @Override
+  public @Nullable ItemStack getChestplate() {
+    return getInventory().getOwnerHandle().getBukkitEntity().getInventory().getChestplate();
+  }
+
+  @Override
+  public void setChestplate(@Nullable ItemStack chestplate) {
+    getInventory().getOwnerHandle().getBukkitEntity().getInventory().setChestplate(chestplate);
+  }
+
+  @Override
+  public @Nullable ItemStack getLeggings() {
+    return getInventory().getOwnerHandle().getBukkitEntity().getInventory().getLeggings();
+  }
+
+  @Override
+  public void setLeggings(@Nullable ItemStack leggings) {
+    getInventory().getOwnerHandle().getBukkitEntity().getInventory().setLeggings(leggings);
+  }
+
+  @Override
+  public @Nullable ItemStack getBoots() {
+    return getInventory().getOwnerHandle().getBukkitEntity().getInventory().getBoots();
+  }
+
+  @Override
+  public void setBoots(@Nullable ItemStack boots) {
+    getInventory().getOwnerHandle().getBukkitEntity().getInventory().setBoots(boots);
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInMainHand() {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    return CraftItemStack.asCraftMirror(internal.getSelectedItem());
+  }
+
+  @Override
+  public void setItemInMainHand(@Nullable ItemStack item) {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    internal.setSelectedItem(CraftItemStack.asNMSCopy(item));
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInOffHand() {
+    return getInventory().getOwnerHandle().getBukkitEntity().getInventory().getItemInOffHand();
+  }
+
+  @Override
+  public void setItemInOffHand(@Nullable ItemStack item) {
+    getInventory().getOwnerHandle().getBukkitEntity().getInventory().setItemInOffHand(item);
+  }
+
+  @SuppressWarnings("InlineMeSuggester")
+  @Deprecated
+  @Override
+  public @NotNull ItemStack getItemInHand() {
+    return getItemInMainHand();
+  }
+
+  @SuppressWarnings("InlineMeSuggester")
+  @Deprecated
+  @Override
+  public void setItemInHand(@Nullable ItemStack stack) {
+    setItemInMainHand(stack);
+  }
+
+  @Override
+  public int getHeldItemSlot() {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    return internal.getNonEquipmentItems().size() - 9 + internal.getSelectedSlot();
+  }
+
+  @Override
+  public void setHeldItemSlot(int slot) {
+    slot %= 9;
+    getInventory().getOwnerHandle().getInventory().setSelectedSlot(slot);
+  }
+
+  @Override
+  public @Nullable ItemStack getItem(@NotNull org.bukkit.inventory.EquipmentSlot slot) {
+    return getInventory().getOwnerHandle().getBukkitEntity().getInventory().getItem(slot);
+  }
+
+  @Override
+  public void setItem(@NotNull org.bukkit.inventory.EquipmentSlot slot, @Nullable ItemStack item) {
+    getInventory().getOwnerHandle().getBukkitEntity().getInventory().setItem(slot, item);
+  }
+
+}

internal/spigot/src/main/java/com/lishid/openinv/internal/reobf/container/slot/ContentEquipment.java

@@ -0,0 +1,116 @@
+package com.lishid.openinv.internal.reobf.container.slot;
+
+import com.lishid.openinv.internal.reobf.container.slot.placeholder.Placeholders;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.craftbukkit.v1_21_R5.CraftEquipmentSlot;
+import org.bukkit.craftbukkit.v1_21_R5.inventory.CraftItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.PlayerInventory;
+import org.jetbrains.annotations.NotNull;
+
+public class ContentEquipment implements Content {
+
+  private PlayerInventory equipment;
+  private final ItemStack placeholder;
+  private final org.bukkit.inventory.EquipmentSlot equipmentSlot;
+
+  public ContentEquipment(ServerPlayer holder, EquipmentSlot equipmentSlot) {
+    setHolder(holder);
+    placeholder = switch (equipmentSlot) {
+      case HEAD -> Placeholders.emptyHelmet;
+      case CHEST -> Placeholders.emptyChestplate;
+      case LEGS -> Placeholders.emptyLeggings;
+      case FEET -> Placeholders.emptyBoots;
+      default -> Placeholders.emptyOffHand;
+    };
+    this.equipmentSlot = CraftEquipmentSlot.getSlot(equipmentSlot);
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.equipment = holder.getBukkitEntity().getInventory();
+  }
+
+  @Override
+  public ItemStack get() {
+    return CraftItemStack.asNMSCopy(equipment.getItem(equipmentSlot));
+  }
+
+  @Override
+  public ItemStack remove() {
+    org.bukkit.inventory.ItemStack old = equipment.getItem(equipmentSlot);
+    equipment.setItem(equipmentSlot, null);
+    return CraftItemStack.asNMSCopy(old);
+  }
+
+  @Override
+  public ItemStack removePartial(int amount) {
+    if (amount <= 0) {
+      return ItemStack.EMPTY;
+    }
+    ItemStack current = get();
+    if (current.isEmpty()) {
+      return ItemStack.EMPTY;
+    }
+    ItemStack split = current.split(amount);
+    set(current);
+    return split;
+  }
+
+  @Override
+  public void set(ItemStack itemStack) {
+    equipment.setItem(equipmentSlot, CraftItemStack.asCraftMirror(itemStack));
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotEquipment(container, slot, x, y);
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return InventoryType.SlotType.ARMOR;
+  }
+
+  public class SlotEquipment extends SlotPlaceholder {
+
+    private ServerPlayer viewer;
+
+    SlotEquipment(Container container, int index, int x, int y) {
+      super(container, index, x, y);
+    }
+
+    @Override
+    public ItemStack getOrDefault() {
+      ItemStack itemStack = getItem();
+      if (!itemStack.isEmpty()) {
+        return itemStack;
+      }
+      return placeholder;
+    }
+
+    public EquipmentSlot getEquipmentSlot() {
+      return CraftEquipmentSlot.getNMS(equipmentSlot);
+    }
+
+    public void onlyEquipmentFor(ServerPlayer viewer) {
+      this.viewer = viewer;
+    }
+
+    @Override
+    public boolean mayPlace(@NotNull ItemStack itemStack) {
+      if (viewer == null) {
+        return true;
+      }
+
+      return equipmentSlot == org.bukkit.inventory.EquipmentSlot.OFF_HAND
+          || viewer.getEquipmentSlotForItem(itemStack) == CraftEquipmentSlot.getNMS(equipmentSlot);
+    }
+
+  }
+
+}

internal/spigot/src/main/java/com/lishid/openinv/internal/reobf/container/slot/ContentOffHand.java

@@ -0,0 +1,50 @@
+package com.lishid.openinv.internal.reobf.container.slot;
+
+import com.lishid.openinv.internal.reobf.player.OpenPlayer;
+import net.minecraft.network.protocol.game.ClientboundContainerSetSlotPacket;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.inventory.InventoryMenu;
+import net.minecraft.world.inventory.Slot;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+public class ContentOffHand extends ContentEquipment {
+
+  private ServerPlayer holder;
+
+  public ContentOffHand(ServerPlayer holder) {
+    super(holder, EquipmentSlot.OFFHAND);
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    super.setHolder(holder);
+    this.holder = holder;
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return InventoryType.SlotType.QUICKBAR;
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotEquipment(container, slot, x, y) {
+      @Override
+      public void setChanged() {
+        if (OpenPlayer.isConnected(holder.connection) && holder.containerMenu != holder.inventoryMenu) {
+          holder.connection.send(
+              new ClientboundContainerSetSlotPacket(
+                  holder.inventoryMenu.containerId,
+                  holder.inventoryMenu.incrementStateId(),
+                  InventoryMenu.SHIELD_SLOT,
+                  holder.getOffhandItem()
+              ));
+        }
+      }
+    };
+  }
+
+}

internal/spigot/src/main/java/com/lishid/openinv/internal/reobf/player/OpenPlayer.java

@@ -0,0 +1,226 @@
+package com.lishid.openinv.internal.reobf.player;
+
+import com.lishid.openinv.event.OpenEvents;
+import com.mojang.logging.LogUtils;
+import net.minecraft.Util;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtIo;
+import net.minecraft.nbt.NumericTag;
+import net.minecraft.nbt.Tag;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.server.network.ServerGamePacketListenerImpl;
+import net.minecraft.util.ProblemReporter;
+import net.minecraft.world.level.storage.PlayerDataStorage;
+import net.minecraft.world.level.storage.TagValueInput;
+import net.minecraft.world.level.storage.TagValueOutput;
+import net.minecraft.world.level.storage.ValueInput;
+import net.minecraft.world.level.storage.ValueOutput;
+import org.bukkit.craftbukkit.v1_21_R5.CraftServer;
+import org.bukkit.craftbukkit.v1_21_R5.entity.CraftPlayer;
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;
+import org.slf4j.Logger;
+
+import java.lang.reflect.Field;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Set;
+
+public class OpenPlayer extends CraftPlayer {
+
+  /**
+   * List of tags to always reset when saving.
+   *
+   * @see net.minecraft.world.entity.Entity#saveWithoutId(ValueOutput)
+   * @see ServerPlayer#addAdditionalSaveData(ValueOutput)
+   * @see net.minecraft.world.entity.player.Player#addAdditionalSaveData(ValueOutput)
+   * @see net.minecraft.world.entity.LivingEntity#addAdditionalSaveData(ValueOutput)
+   */
+  @Unmodifiable
+  protected static final Set<String> RESET_TAGS = Set.of(
+      // Entity#saveWithoutId(CompoundTag)
+      "CustomName",
+      "CustomNameVisible",
+      "Silent",
+      "NoGravity",
+      "Glowing",
+      "TicksFrozen",
+      "HasVisualFire",
+      "Tags",
+      "Passengers",
+      // ServerPlayer#addAdditionalSaveData(CompoundTag)
+      // Intentional omissions to prevent mount loss: Attach, Entity, and RootVehicle
+      "warden_spawn_tracker",
+      "entered_nether_pos", // Replaces enteredNetherPosition
+      "enteredNetherPosition",
+      "respawn", // Replaces SpawnXyz fields as of 1.21.6
+      "SpawnX",
+      "SpawnY",
+      "SpawnZ",
+      "SpawnForced",
+      "SpawnAngle",
+      "SpawnDimension",
+      "raid_omen_position",
+      "ender_pearls",
+      // Player#addAdditionalSaveData(CompoundTag)
+      "ShoulderEntityLeft",
+      "ShoulderEntityRight",
+      "LastDeathLocation",
+      "current_explosion_impact_pos",
+      // LivingEntity#addAdditionalSaveData(CompoundTag)
+      "active_effects",
+      "sleeping_pos", // Replaces SleepingXyz fields as of 1.21.6
+      "SleepingX",
+      "SleepingY",
+      "SleepingZ",
+      "Brain",
+      "last_hurt_by_player",
+      "last_hurt_by_player_memory_time",
+      "last_hurt_by_mob",
+      "ticks_since_last_hurt_by_mob",
+      "equipment",
+      "locator_bar_icon"
+  );
+
+  private final PlayerManager manager;
+
+  protected OpenPlayer(CraftServer server, ServerPlayer entity, PlayerManager manager) {
+    super(server, entity);
+    this.manager = manager;
+  }
+
+  @Override
+  public void loadData() {
+    manager.loadData(getHandle());
+  }
+
+  @Override
+  public void saveData() {
+    if (OpenEvents.saveCancelled(this)) {
+      return;
+    }
+
+    ServerPlayer player = this.getHandle();
+    Logger logger = LogUtils.getLogger();
+    // See net.minecraft.world.level.storage.PlayerDataStorage#save(EntityHuman)
+    try (ProblemReporter.ScopedCollector scopedCollector = new ProblemReporter.ScopedCollector(player.problemPath(), logger)) {
+      PlayerDataStorage worldNBTStorage = server.getServer().getPlayerList().playerIo;
+
+      ValueInput oldDataInput = isOnline()
+          ? null
+          : worldNBTStorage.load(player.getName().getString(), player.getStringUUID(), scopedCollector, player.registryAccess()).orElse(null);
+      // Grab CompoundTag out of TagValueInput - we can't iterate over the fields via TagValueInput.
+      CompoundTag oldData = null;
+      if (oldDataInput != null) {
+        Field tagValueInputInput = TagValueInput.class.getDeclaredField("input");
+        tagValueInputInput.setAccessible(true);
+        oldData = (CompoundTag) tagValueInputInput.get(oldDataInput);
+      }
+
+      CompoundTag playerData = getWritableTag(oldData);
+
+      ValueOutput valueOutput = TagValueOutput.createWithContext(scopedCollector, player.registryAccess());
+      Field tagValueOutputOutput = TagValueOutput.class.getDeclaredField("output");
+      tagValueOutputOutput.setAccessible(true);
+      CompoundTag newPlayerData = (CompoundTag) tagValueOutputOutput.get(valueOutput);
+      // Add existing old data.
+      newPlayerData.merge(playerData);
+      playerData = newPlayerData;
+
+      player.saveWithoutId(valueOutput);
+
+      if (oldData != null) {
+        // Revert certain special data values when offline.
+        revertSpecialValues(playerData, oldData);
+      }
+
+      Path playerDataDir = worldNBTStorage.getPlayerDir().toPath();
+      Path tempFile = Files.createTempFile(playerDataDir, player.getStringUUID() + "-", ".dat");
+      NbtIo.writeCompressed(playerData, tempFile);
+      Path dataFile = playerDataDir.resolve(player.getStringUUID() + ".dat");
+      Path backupFile = playerDataDir.resolve(player.getStringUUID() + ".dat_old");
+      Util.safeReplaceFile(dataFile, tempFile, backupFile);
+    } catch (Exception e) {
+      LogUtils.getLogger().warn("Failed to save player data for {}: {}", player.getScoreboardName(), e);
+    }
+  }
+
+  @Contract("null -> new")
+  protected @NotNull CompoundTag getWritableTag(@Nullable CompoundTag oldData) {
+    if (oldData == null) {
+      return new CompoundTag();
+    }
+
+    // Copy old data. This is a deep clone, so operating on it should be safe.
+    oldData = oldData.copy();
+
+    // Remove vanilla/server data that is not written every time.
+    oldData.keySet().removeIf(
+        key -> RESET_TAGS.contains(key)
+            || key.startsWith("Bukkit")
+            || (key.startsWith("Paper") && key.length() > 5)
+    );
+
+    return oldData;
+  }
+
+  protected void revertSpecialValues(@NotNull CompoundTag newData, @NotNull CompoundTag oldData) {
+    // Revert automatic updates to play timestamps.
+    copyValue(oldData, newData, "bukkit", "lastPlayed", NumericTag.class);
+    copyValue(oldData, newData, "Paper", "LastSeen", NumericTag.class);
+    copyValue(oldData, newData, "Paper", "LastLogin", NumericTag.class);
+  }
+
+  private <T extends Tag> void copyValue(
+      @NotNull CompoundTag source,
+      @NotNull CompoundTag target,
+      @NotNull String container,
+      @NotNull String key,
+      @SuppressWarnings("SameParameterValue") @NotNull Class<T> tagType
+  ) {
+    CompoundTag oldContainer = getTag(source, container, CompoundTag.class);
+    CompoundTag newContainer = getTag(target, container, CompoundTag.class);
+
+    // New container being null means the server implementation doesn't store this data.
+    if (newContainer == null) {
+      return;
+    }
+
+    // If old tag exists, copy it to new location, removing otherwise.
+    setTag(newContainer, key, getTag(oldContainer, key, tagType));
+  }
+
+  private <T extends Tag> @Nullable T getTag(
+      @Nullable CompoundTag container,
+      @NotNull String key,
+      @NotNull Class<T> dataType
+  ) {
+    if (container == null) {
+      return null;
+    }
+    Tag value = container.get(key);
+    if (value == null || !dataType.isAssignableFrom(value.getClass())) {
+      return null;
+    }
+    return dataType.cast(value);
+  }
+
+  private <T extends Tag> void setTag(
+      @NotNull CompoundTag container,
+      @NotNull String key,
+      @Nullable T data
+  ) {
+    if (data == null) {
+      container.remove(key);
+    } else {
+      container.put(key, data);
+    }
+  }
+
+  public static boolean isConnected(@Nullable ServerGamePacketListenerImpl connection) {
+    return connection != null && !connection.isDisconnected();
+  }
+
+}

internal/spigot/src/main/java/com/lishid/openinv/internal/reobf/player/PlayerManager.java

@@ -3,8 +3,8 @@ package com.lishid.openinv.internal.reobf.player;
 import com.lishid.openinv.internal.ISpecialInventory;
 import com.lishid.openinv.internal.reobf.container.OpenEnderChest;
 import com.lishid.openinv.internal.reobf.container.OpenInventory;
+import com.lishid.openinv.util.JulLoggerAdapter;
 import com.mojang.authlib.GameProfile;
-import net.minecraft.nbt.CompoundTag;
 import net.minecraft.network.chat.Component;
 import net.minecraft.network.protocol.game.ClientboundOpenScreenPacket;
 import net.minecraft.server.MinecraftServer;
@@ -12,16 +12,18 @@ import net.minecraft.server.level.ClientInformation;
 import net.minecraft.server.level.ParticleStatus;
 import net.minecraft.server.level.ServerLevel;
 import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.util.ProblemReporter;
 import net.minecraft.world.entity.Entity;
 import net.minecraft.world.entity.player.ChatVisiblity;
 import net.minecraft.world.inventory.AbstractContainerMenu;
 import net.minecraft.world.level.Level;
+import net.minecraft.world.level.storage.ValueInput;
 import org.bukkit.Bukkit;
 import org.bukkit.OfflinePlayer;
 import org.bukkit.Server;
-import org.bukkit.craftbukkit.v1_21_R3.CraftServer;
-import org.bukkit.craftbukkit.v1_21_R3.entity.CraftPlayer;
-import org.bukkit.craftbukkit.v1_21_R3.event.CraftEventFactory;
+import org.bukkit.craftbukkit.v1_21_R5.CraftServer;
+import org.bukkit.craftbukkit.v1_21_R5.entity.CraftPlayer;
+import org.bukkit.craftbukkit.v1_21_R5.event.CraftEventFactory;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.InventoryView;
 import org.jetbrains.annotations.NotNull;
@@ -47,15 +49,15 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
   }
 
   public static @NotNull ServerPlayer getHandle(final Player player) {
-    if (player instanceof CraftPlayer) {
-      return ((CraftPlayer) player).getHandle();
+    if (player instanceof CraftPlayer craftPlayer) {
+      return craftPlayer.getHandle();
     }
 
     Server server = player.getServer();
     ServerPlayer nmsPlayer = null;
 
-    if (server instanceof CraftServer) {
-      nmsPlayer = ((CraftServer) server).getHandle().getPlayer(player.getUniqueId());
+    if (server instanceof CraftServer craftServer) {
+      nmsPlayer = craftServer.getHandle().getPlayer(player.getUniqueId());
     }
 
     if (nmsPlayer == null) {
@@ -68,7 +70,11 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
 
   @Override
   public @Nullable Player loadPlayer(@NotNull final OfflinePlayer offline) {
-    MinecraftServer server = ((CraftServer) Bukkit.getServer()).getServer();
+    if (!(Bukkit.getServer() instanceof CraftServer craftServer)) {
+      return null;
+    }
+
+    MinecraftServer server = craftServer.getServer();
     ServerLevel worldServer = server.getLevel(Level.OVERWORLD);
 
     if (worldServer == null) {
@@ -93,11 +99,13 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
   private @NotNull ServerPlayer createNewPlayer(
       @NotNull MinecraftServer server,
       @NotNull ServerLevel worldServer,
-      @NotNull final OfflinePlayer offline) {
+      @NotNull final OfflinePlayer offline
+  ) {
     // See net.minecraft.server.players.PlayerList#canPlayerLogin(ServerLoginPacketListenerImpl, GameProfile)
     // See net.minecraft.server.network.ServerLoginPacketListenerImpl#handleHello(ServerboundHelloPacket)
     GameProfile profile = new GameProfile(offline.getUniqueId(),
-        offline.getName() != null ? offline.getName() : offline.getUniqueId().toString());
+        offline.getName() != null ? offline.getName() : offline.getUniqueId().toString()
+    );
 
     ClientInformation dummyInfo = new ClientInformation(
         "en_us",
@@ -119,7 +127,8 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
       logger.log(
           java.util.logging.Level.WARNING,
           e,
-          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!");
+          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!"
+      );
     }
 
     return entity;
@@ -127,20 +136,21 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
 
   boolean loadData(@NotNull ServerPlayer player) {
     // See CraftPlayer#loadData
-    CompoundTag loadedData = player.server.getPlayerList().playerIo.load(player).orElse(null);
 
-    if (loadedData == null) {
-      // Exceptions with loading are logged by Mojang.
-      return false;
+    try (ProblemReporter.ScopedCollector scopedCollector = new ProblemReporter.ScopedCollector(player.problemPath(), new JulLoggerAdapter(logger))) {
+      ValueInput loadedData = player.server.getPlayerList().playerIo.load(player, scopedCollector).orElse(null);
+
+      if (loadedData == null) {
+        // Exceptions with loading are logged.
+        return false;
+      }
+
+      // Read basic data into the player.
+      player.load(loadedData);
+      // Game type settings are loaded separately.
+      player.loadGameTypes(loadedData);
     }
 
-    // Read basic data into the player.
-    player.load(loadedData);
-    // Also read "extra" data.
-    player.readAdditionalSaveData(loadedData);
-    // Game type settings are also loaded separately.
-    player.loadGameTypes(loadedData);
-
     return true;
   }
 
@@ -167,13 +177,17 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
       logger.log(
           java.util.logging.Level.WARNING,
           e,
-          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!");
+          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!"
+      );
       return player;
     }
   }
 
   @Override
-  public @Nullable InventoryView openInventory(@NotNull Player bukkitPlayer, @NotNull ISpecialInventory inventory, boolean viewOnly) {
+  public @Nullable InventoryView openInventory(
+      @NotNull Player bukkitPlayer, @NotNull ISpecialInventory inventory,
+      boolean viewOnly
+  ) {
     ServerPlayer player = getHandle(bukkitPlayer);
 
     if (!OpenPlayer.isConnected(player.connection)) {

jitpack.yml

@@ -3,4 +3,4 @@ before_install:
   - sdk install java 21-tem
   - sdk use java 21-tem
 install:
-  - ./gradlew :openinvapi:publishJitpackPublicationToMavenLocal
+  - ./gradlew -Djitpack=true :openinvapi:publishJitpackPublicationToMavenLocal

plugin/build.gradle.kts

@@ -1,3 +1,5 @@
+import com.github.jikoo.openinv.SpigotReobf
+
 plugins {
   `openinv-base`
   alias(libs.plugins.shadow)
@@ -11,10 +13,13 @@ dependencies {
   implementation(project(":openinvapi"))
   implementation(project(":openinvcommon"))
   implementation(project(":openinvadaptercommon"))
+  implementation(project(":openinvadapterpaper1_21_5"))
+  implementation(project(":openinvadapterpaper1_21_4"))
   implementation(project(":openinvadapterpaper1_21_3"))
   implementation(project(":openinvadapterpaper1_21_1"))
-  implementation(project(":openinvadapterspigot", configuration = "shadow"))
+  implementation(project(":openinvadapterspigot", configuration = SpigotReobf.ARTIFACT_CONFIG))
   implementation(libs.planarwrappers)
+  implementation(libs.folia.scheduler.wrapper)
 }
 
 tasks.processResources {
@@ -26,9 +31,11 @@ tasks.jar {
 }
 
 tasks.shadowJar {
-  dependsOn(":openinvadapterspigot:reobf")
+  relocate("me.nahu.scheduler.wrapper", "com.github.jikoo.openinv.lib.nahu.scheduler-wrapper")
+  relocate("com.github.jikoo.planarwrappers", "com.github.jikoo.openinv.lib.planarwrappers")
   minimize {
     exclude(":openinv**")
+    exclude(dependency(libs.folia.scheduler.wrapper.get()))
   }
 }
 

plugin/src/main/java/com/lishid/openinv/OpenInv.java

@@ -16,6 +16,7 @@
 
 package com.lishid.openinv;
 
+import com.lishid.openinv.command.ClearInvCommand;
 import com.lishid.openinv.command.ContainerSettingCommand;
 import com.lishid.openinv.command.OpenInvCommand;
 import com.lishid.openinv.command.SearchContainerCommand;
@@ -38,6 +39,7 @@ import com.lishid.openinv.util.lang.LangMigrator;
 import com.lishid.openinv.util.lang.LanguageManager;
 import com.lishid.openinv.util.setting.PlayerToggle;
 import com.lishid.openinv.util.setting.PlayerToggles;
+import me.nahu.scheduler.wrapper.FoliaWrappedJavaPlugin;
 import org.bukkit.OfflinePlayer;
 import org.bukkit.command.Command;
 import org.bukkit.command.CommandExecutor;
@@ -47,7 +49,6 @@ import org.bukkit.entity.HumanEntity;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.InventoryView;
 import org.bukkit.plugin.PluginManager;
-import org.bukkit.plugin.java.JavaPlugin;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -59,245 +60,251 @@ import java.util.function.Consumer;
 /**
  * The main class for OpenInv.
  */
-public class OpenInv extends JavaPlugin implements IOpenInv {
+public class OpenInv extends FoliaWrappedJavaPlugin implements IOpenInv {
 
-    private InternalAccessor accessor;
-    private Config config;
-    private InventoryManager inventoryManager;
-    private LanguageManager languageManager;
-    private PlayerLoader playerLoader;
-    private boolean isSpigot = false;
+  private InternalAccessor accessor;
+  private Config config;
+  private InventoryManager inventoryManager;
+  private LanguageManager languageManager;
+  private PlayerLoader playerLoader;
+  private boolean isSpigot = false;
 
-    @Override
-    public void reloadConfig() {
-        super.reloadConfig();
-        config.reload(getConfig());
-        languageManager.reload();
-        if (accessor != null && accessor.isSupported()) {
-            accessor.reload(getConfig());
+  @Override
+  public void reloadConfig() {
+    super.reloadConfig();
+    config.reload(getConfig());
+    languageManager.reload();
+    if (accessor != null && accessor.isSupported()) {
+      accessor.reload(getConfig());
+    }
+  }
+
+  @Override
+  public boolean onCommand(
+      @NotNull CommandSender sender,
+      @NotNull Command command,
+      @NotNull String label,
+      @NotNull String[] args
+  ) {
+    if (!isSpigot || !this.accessor.isSupported()) {
+      this.sendVersionError(sender::sendMessage);
+      return true;
+    }
+    return false;
+  }
+
+  @Override
+  public void onDisable() {
+    inventoryManager.evictAll();
+  }
+
+  @Override
+  public void onEnable() {
+    // Save default configuration if not present.
+    this.saveDefaultConfig();
+
+    // Migrate locale files to a subfolder.
+    Path dataFolder = getDataFolder().toPath();
+    new LangMigrator(dataFolder, dataFolder.resolve("locale"), getLogger()).migrate();
+
+    // Set up configurable features. Note that #reloadConfig is called on the first call to #getConfig!
+    // Configuration values should not be accessed until after all of these have been set up.
+    config = new Config();
+    languageManager = new LanguageManager(this, "en");
+    accessor = new InternalAccessor(getLogger(), languageManager);
+
+    // Perform initial config load.
+    reloadConfig();
+
+    inventoryManager = new InventoryManager(this, config, accessor);
+    playerLoader = new PlayerLoader(this, config, inventoryManager, accessor, getLogger());
+
+    try {
+      Class.forName("org.bukkit.entity.Player$Spigot");
+      isSpigot = true;
+    } catch (ClassNotFoundException e) {
+      isSpigot = false;
+    }
+
+    // Version check
+    if (isSpigot && this.accessor.isSupported()) {
+      reloadConfig();
+
+      // Update existing configuration. May require internal access.
+      new ConfigUpdater(this).checkForUpdates();
+
+      // Register relevant event listeners.
+      registerEvents();
+
+      // Register commands to their executors.
+      registerCommands();
+
+    } else {
+      this.sendVersionError(this.getLogger()::warning);
+    }
+
+  }
+
+  private void registerEvents() {
+    PluginManager pluginManager = this.getServer().getPluginManager();
+    pluginManager.registerEvents(playerLoader, this);
+    pluginManager.registerEvents(inventoryManager, this);
+    pluginManager.registerEvents(new ContainerListener(accessor, languageManager), this);
+    pluginManager.registerEvents(new ToggleListener(), this);
+  }
+
+  private void registerCommands() {
+    this.setCommandExecutor(new OpenInvCommand(this, config, inventoryManager, languageManager, playerLoader), "openinv", "openender");
+    this.setCommandExecutor(new SearchContainerCommand(this, languageManager), "searchcontainer");
+    this.setCommandExecutor(new SearchInvCommand(languageManager), "searchinv", "searchender");
+    this.setCommandExecutor(new SearchEnchantCommand(languageManager), "searchenchant");
+    this.setCommandExecutor(new ClearInvCommand(this, config, inventoryManager, languageManager, playerLoader), "clearinv", "clearender");
+
+    ContainerSettingCommand settingCommand = new ContainerSettingCommand(languageManager);
+    for (PlayerToggle toggle : PlayerToggles.get()) {
+      setCommandExecutor(settingCommand, toggle.getName().toLowerCase(Locale.ENGLISH));
+    }
+  }
+
+  private void setCommandExecutor(@NotNull CommandExecutor executor, String @NotNull ... commands) {
+    for (String commandName : commands) {
+      PluginCommand command = this.getCommand(commandName);
+      if (command != null) {
+        command.setExecutor(executor);
+      }
+    }
+  }
+
+  private void sendVersionError(@NotNull Consumer<String> messageMethod) {
+    if (!accessor.isSupported()) {
+      messageMethod.accept("Your server version (" + accessor.getVersion() + ") is not supported.");
+      messageMethod.accept("Please download the correct version of OpenInv here: " + accessor.getReleasesLink());
+    }
+    if (!isSpigot) {
+      messageMethod.accept("OpenInv requires that you use Spigot or a Spigot fork. Per the 1.14 update thread");
+      messageMethod.accept("(https://www.spigotmc.org/threads/369724/ \"A Note on CraftBukkit\"), if you are");
+      messageMethod.accept("encountering an inconsistency with vanilla that prevents you from using Spigot,");
+      messageMethod.accept("that is considered a Spigot bug and should be reported as such.");
+    }
+  }
+
+  @Override
+  public boolean isSupportedVersion() {
+    return this.accessor != null && this.accessor.isSupported();
+  }
+
+  @Override
+  public boolean disableSaving() {
+    return config.isSaveDisabled();
+  }
+
+  @Override
+  public boolean disableOfflineAccess() {
+    return config.isOfflineDisabled();
+  }
+
+  @Override
+  public boolean noArgsOpensSelf() {
+    return config.doesNoArgsOpenSelf();
+  }
+
+  @Override
+  public @NotNull IAnySilentContainer getAnySilentContainer() {
+    return this.accessor.getAnySilentContainer();
+  }
+
+  @Override
+  public boolean getAnyContainerStatus(@NotNull final OfflinePlayer offline) {
+    return PlayerToggles.any().is(offline.getUniqueId());
+  }
+
+  @Override
+  public void setAnyContainerStatus(@NotNull final OfflinePlayer offline, final boolean status) {
+    PlayerToggles.any().set(offline.getUniqueId(), status);
+  }
+
+  @Override
+  public boolean getSilentContainerStatus(@NotNull final OfflinePlayer offline) {
+    return PlayerToggles.silent().is(offline.getUniqueId());
+  }
+
+  @Override
+  public void setSilentContainerStatus(@NotNull final OfflinePlayer offline, final boolean status) {
+    PlayerToggles.silent().set(offline.getUniqueId(), status);
+  }
+
+  @Override
+  public @NotNull ISpecialEnderChest getSpecialEnderChest(@NotNull final Player player, final boolean online) {
+    return inventoryManager.getEnderChest(player);
+  }
+
+  @Override
+  public @NotNull ISpecialPlayerInventory getSpecialInventory(@NotNull final Player player, final boolean online) {
+    return inventoryManager.getInventory(player);
+  }
+
+  @Override
+  public @Nullable InventoryView openInventory(@NotNull Player player, @NotNull ISpecialInventory inventory) {
+    Permissions edit = null;
+    HumanEntity target = inventory.getPlayer();
+    boolean ownContainer = player.equals(target);
+    if (inventory instanceof ISpecialPlayerInventory) {
+      edit = ownContainer ? Permissions.INVENTORY_EDIT_SELF : Permissions.INVENTORY_EDIT_OTHER;
+    } else if (inventory instanceof ISpecialEnderChest) {
+      edit = ownContainer ? Permissions.ENDERCHEST_EDIT_SELF : Permissions.ENDERCHEST_EDIT_OTHER;
+    }
+
+    boolean viewOnly = edit != null && !edit.hasPermission(player);
+
+    if (ownContainer || (viewOnly && config.getAccessEqualMode() != AccessEqualMode.DENY)) {
+      return this.accessor.openInventory(player, inventory, viewOnly);
+    }
+
+    for (int level = 4; level > 0; --level) {
+      String permission = "openinv.access.level." + level;
+      // If the target doesn't have this access level...
+      if (!target.hasPermission(permission)) {
+        // If the viewer does have the access level, all good.
+        if (player.hasPermission(permission)) {
+          break;
         }
+        // Otherwise check next access level.
+        continue;
+      }
+
+      // If the viewer doesn't have an equal access level or equal access is a denial, deny.
+      if (!player.hasPermission(permission) || config.getAccessEqualMode() == AccessEqualMode.DENY) {
+        return null;
+      }
+
+      // Since this is a tie, setting decides view state.
+      if (config.getAccessEqualMode() == AccessEqualMode.VIEW) {
+        viewOnly = true;
+      }
+      break;
     }
 
-    @Override
-    public boolean onCommand(@NotNull CommandSender sender, @NotNull Command command, @NotNull String label, @NotNull String[] args) {
-        if (!isSpigot || !this.accessor.isSupported()) {
-            this.sendVersionError(sender::sendMessage);
-            return true;
-        }
-        return false;
-    }
+    return this.accessor.openInventory(player, inventory, viewOnly);
+  }
 
-    @Override
-    public void onDisable() {
-        inventoryManager.evictAll();
-    }
+  @Override
+  public boolean isPlayerLoaded(@NotNull UUID playerUuid) {
+    return inventoryManager.getLoadedPlayer(playerUuid) != null;
+  }
 
-    @Override
-    public void onEnable() {
-        // Save default configuration if not present.
-        this.saveDefaultConfig();
+  @Override
+  public @Nullable Player loadPlayer(@NotNull final OfflinePlayer offline) {
+    return playerLoader.load(offline);
+  }
 
-        // Migrate locale files to a subfolder.
-        Path dataFolder = getDataFolder().toPath();
-        new LangMigrator(dataFolder, dataFolder.resolve("locale"), getLogger()).migrate();
+  @Override
+  public @Nullable OfflinePlayer matchPlayer(@NotNull String name) {
+    return playerLoader.match(name);
+  }
 
-        // Set up configurable features. Note that #reloadConfig is called on the first call to #getConfig!
-        // Configuration values should not be accessed until after all of these have been set up.
-        config = new Config();
-        languageManager = new LanguageManager(this, "en");
-        accessor = new InternalAccessor(getLogger(), languageManager);
-
-        // Perform initial config load.
-        reloadConfig();
-
-        inventoryManager = new InventoryManager(this, config, accessor);
-        playerLoader = new PlayerLoader(this, config, inventoryManager, accessor, getLogger());
-
-        try {
-            Class.forName("org.bukkit.entity.Player$Spigot");
-            isSpigot = true;
-        } catch (ClassNotFoundException e) {
-            isSpigot = false;
-        }
-
-        // Version check
-        if (isSpigot && this.accessor.isSupported()) {
-            reloadConfig();
-
-            // Update existing configuration. May require internal access.
-            new ConfigUpdater(this).checkForUpdates();
-
-            // Register relevant event listeners.
-            registerEvents();
-
-            // Register commands to their executors.
-            registerCommands();
-
-        } else {
-            this.sendVersionError(this.getLogger()::warning);
-        }
-
-    }
-
-    private void registerEvents() {
-        PluginManager pluginManager = this.getServer().getPluginManager();
-        pluginManager.registerEvents(playerLoader, this);
-        pluginManager.registerEvents(inventoryManager, this);
-        pluginManager.registerEvents(new ContainerListener(accessor, languageManager), this);
-        pluginManager.registerEvents(new ToggleListener(), this);
-    }
-
-    private void registerCommands() {
-        this.setCommandExecutor(new OpenInvCommand(this, config, inventoryManager, languageManager, playerLoader), "openinv", "openender");
-        this.setCommandExecutor(new SearchContainerCommand(this, languageManager), "searchcontainer");
-        this.setCommandExecutor(new SearchInvCommand(languageManager), "searchinv", "searchender");
-        this.setCommandExecutor(new SearchEnchantCommand(languageManager), "searchenchant");
-
-        ContainerSettingCommand settingCommand = new ContainerSettingCommand(languageManager);
-        for (PlayerToggle toggle : PlayerToggles.get()) {
-            setCommandExecutor(settingCommand, toggle.getName().toLowerCase(Locale.ENGLISH));
-        }
-    }
-
-    private void setCommandExecutor(@NotNull CommandExecutor executor, String @NotNull ... commands) {
-        for (String commandName : commands) {
-            PluginCommand command = this.getCommand(commandName);
-            if (command != null) {
-                command.setExecutor(executor);
-            }
-        }
-    }
-
-    private void sendVersionError(@NotNull Consumer<String> messageMethod) {
-        if (!accessor.isSupported()) {
-            messageMethod.accept("Your server version (" + accessor.getVersion() + ") is not supported.");
-            messageMethod.accept("Please download the correct version of OpenInv here: " + accessor.getReleasesLink());
-        }
-        if (!isSpigot) {
-            messageMethod.accept("OpenInv requires that you use Spigot or a Spigot fork. Per the 1.14 update thread");
-            messageMethod.accept("(https://www.spigotmc.org/threads/369724/ \"A Note on CraftBukkit\"), if you are");
-            messageMethod.accept("encountering an inconsistency with vanilla that prevents you from using Spigot,");
-            messageMethod.accept("that is considered a Spigot bug and should be reported as such.");
-        }
-    }
-
-    @Override
-    public boolean isSupportedVersion() {
-        return this.accessor != null && this.accessor.isSupported();
-    }
-
-    @Override
-    public boolean disableSaving() {
-        return config.isSaveDisabled();
-    }
-
-    @Override
-    public boolean disableOfflineAccess() {
-        return config.isOfflineDisabled();
-    }
-
-    @Override
-    public boolean noArgsOpensSelf() {
-        return config.doesNoArgsOpenSelf();
-    }
-
-    @Override
-    public @NotNull IAnySilentContainer getAnySilentContainer() {
-        return this.accessor.getAnySilentContainer();
-    }
-
-    @Override
-    public boolean getAnyContainerStatus(@NotNull final OfflinePlayer offline) {
-        return PlayerToggles.any().is(offline.getUniqueId());
-    }
-
-    @Override
-    public void setAnyContainerStatus(@NotNull final OfflinePlayer offline, final boolean status) {
-        PlayerToggles.any().set(offline.getUniqueId(), status);
-    }
-
-    @Override
-    public boolean getSilentContainerStatus(@NotNull final OfflinePlayer offline) {
-        return PlayerToggles.silent().is(offline.getUniqueId());
-    }
-
-    @Override
-    public void setSilentContainerStatus(@NotNull final OfflinePlayer offline, final boolean status) {
-        PlayerToggles.silent().set(offline.getUniqueId(), status);
-    }
-
-    @Override
-    public @NotNull ISpecialEnderChest getSpecialEnderChest(@NotNull final Player player, final boolean online) {
-        return inventoryManager.getEnderChest(player);
-    }
-
-    @Override
-    public @NotNull ISpecialPlayerInventory getSpecialInventory(@NotNull final Player player, final boolean online) {
-        return inventoryManager.getInventory(player);
-    }
-
-    @Override
-    public @Nullable InventoryView openInventory(@NotNull Player player, @NotNull ISpecialInventory inventory) {
-        Permissions edit = null;
-        HumanEntity target = inventory.getPlayer();
-        boolean ownContainer = player.equals(target);
-        if (inventory instanceof ISpecialPlayerInventory) {
-            edit = ownContainer ? Permissions.INVENTORY_EDIT_SELF : Permissions.INVENTORY_EDIT_OTHER;
-        } else if (inventory instanceof ISpecialEnderChest) {
-            edit = ownContainer ? Permissions.ENDERCHEST_EDIT_SELF : Permissions.ENDERCHEST_EDIT_OTHER;
-        }
-
-        boolean viewOnly = edit != null && !edit.hasPermission(player);
-
-        if (ownContainer || viewOnly && config.getAccessEqualMode() != AccessEqualMode.DENY) {
-            return this.accessor.openInventory(player, inventory, viewOnly);
-        }
-
-        for (int level = 4; level > 0; --level) {
-            String permission = "openinv.access.level." + level;
-            // If the target doesn't have this access level...
-            if (!target.hasPermission(permission)) {
-                // If the viewer does have the access level, all good.
-                if (player.hasPermission(permission)) {
-                    break;
-                }
-                // Otherwise check next access level.
-                continue;
-            }
-
-            // If the viewer doesn't have an equal access level or equal access is a denial, deny.
-            if (!player.hasPermission(permission) || config.getAccessEqualMode() == AccessEqualMode.DENY) {
-                return null;
-            }
-
-            // Since this is a tie, setting decides view state.
-            if (config.getAccessEqualMode() == AccessEqualMode.VIEW) {
-                viewOnly = true;
-            }
-            break;
-        }
-
-        return this.accessor.openInventory(player, inventory, viewOnly);
-    }
-
-    @Override
-    public boolean isPlayerLoaded(@NotNull UUID playerUuid) {
-        return inventoryManager.getLoadedPlayer(playerUuid) != null;
-    }
-
-    @Override
-    public @Nullable Player loadPlayer(@NotNull final OfflinePlayer offline) {
-        return playerLoader.load(offline);
-    }
-
-    @Override
-    public @Nullable OfflinePlayer matchPlayer(@NotNull String name) {
-        return playerLoader.match(name);
-    }
-
-    @Override
-    public void unload(@NotNull final OfflinePlayer offline) {
-        inventoryManager.unload(offline.getUniqueId());
-    }
+  @Override
+  public void unload(@NotNull final OfflinePlayer offline) {
+    inventoryManager.unload(offline.getUniqueId());
+  }
 
 }

plugin/src/main/java/com/lishid/openinv/command/ClearInvCommand.java

@@ -0,0 +1,128 @@
+package com.lishid.openinv.command;
+
+import com.lishid.openinv.OpenInv;
+import com.lishid.openinv.internal.ISpecialInventory;
+import com.lishid.openinv.util.InventoryManager;
+import com.lishid.openinv.util.Permissions;
+import com.lishid.openinv.util.PlayerLoader;
+import com.lishid.openinv.util.config.Config;
+import com.lishid.openinv.util.lang.LanguageManager;
+import com.lishid.openinv.util.lang.Replacement;
+import org.bukkit.OfflinePlayer;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+import java.util.logging.Level;
+
+public class ClearInvCommand extends PlayerLookupCommand {
+
+  private final @NotNull InventoryManager manager;
+
+  public ClearInvCommand(
+      @NotNull OpenInv plugin,
+      @NotNull Config config,
+      @NotNull InventoryManager manager,
+      @NotNull LanguageManager lang,
+      @NotNull PlayerLoader playerLoader
+  ) {
+    super(plugin, lang, config, playerLoader);
+    this.manager = manager;
+  }
+
+  @Override
+  protected boolean isAccessInventory(@NotNull Command command) {
+    return command.getName().equals("clearinv");
+  }
+
+  @Override
+  protected @Nullable String getTargetIdentifer(
+      @NotNull CommandSender sender,
+      @NotNull Command command,
+      @Nullable String argument,
+      boolean accessInv
+  ) {
+    if (!Permissions.CLEAR_OTHER.hasPermission(sender)) {
+      // If the sender does not have permissions to clear others, use self.
+      if (sender instanceof Player player) {
+        return player.getUniqueId().toString();
+      }
+
+      // Console can't target itself. Send error.
+      lang.sendMessage(sender, "messages.error.permissionOpenOther");
+      return null;
+    }
+
+    // If argument is provided, use it.
+    if (argument != null) {
+      return argument;
+    }
+
+    // For players, default to self.
+    if (sender instanceof Player player) {
+      return player.getUniqueId().toString();
+    }
+
+    // For console, argument is required. Send usage.
+    sender.sendMessage(command.getUsage());
+    return null;
+  }
+
+  @Override
+  protected @Nullable OfflinePlayer getTarget(@NotNull String identifier) {
+    return playerLoader.matchExact(identifier);
+  }
+
+  @Override
+  protected boolean deniedCommand(@NotNull CommandSender sender, @NotNull Player onlineTarget, boolean accessInv) {
+    if (onlineTarget.equals(sender)) {
+      return !Permissions.CLEAR_SELF.hasPermission(sender);
+    }
+    return !Permissions.CLEAR_OTHER.hasPermission(sender);
+  }
+
+  @Override
+  protected void handle(
+      @NotNull CommandSender sender,
+      @NotNull Player onlineTarget,
+      boolean accessInv,
+      @NotNull String @NotNull [] args
+  ) {
+    // Create the inventory
+    final ISpecialInventory inv;
+    try {
+      inv = accessInv ? manager.getInventory(onlineTarget) : manager.getEnderChest(onlineTarget);
+    } catch (Exception e) {
+      lang.sendMessage(sender, "messages.error.commandException");
+      plugin.getLogger().log(Level.WARNING, "Unable to create ISpecialInventory", e);
+      return;
+    }
+
+    // Clear the inventory
+    inv.getBukkitInventory().clear();
+    manager.save(onlineTarget.getUniqueId());
+    lang.sendMessage(
+        sender,
+        accessInv ? "messages.info.clear.inventory" : "messages.info.clear.enderchest",
+        new Replacement("%target%", onlineTarget.getDisplayName())
+    );
+  }
+
+  @Override
+  public List<String> onTabComplete(
+      @NotNull CommandSender sender,
+      @NotNull Command command,
+      @NotNull String label,
+      @NotNull String[] args
+  ) {
+    if (!Permissions.CLEAR_OTHER.hasPermission(sender)) {
+      return List.of();
+    }
+
+    return super.onTabComplete(sender, command, label, args);
+  }
+
+}

plugin/src/main/java/com/lishid/openinv/command/ContainerSettingCommand.java

@@ -17,11 +17,11 @@
 package com.lishid.openinv.command;
 
 import com.lishid.openinv.event.OpenEvents;
-import com.lishid.openinv.util.setting.PlayerToggle;
 import com.lishid.openinv.util.TabCompleter;
-import com.lishid.openinv.util.setting.PlayerToggles;
 import com.lishid.openinv.util.lang.LanguageManager;
 import com.lishid.openinv.util.lang.Replacement;
+import com.lishid.openinv.util.setting.PlayerToggle;
+import com.lishid.openinv.util.setting.PlayerToggles;
 import org.bukkit.command.Command;
 import org.bukkit.command.CommandSender;
 import org.bukkit.command.TabExecutor;
@@ -36,72 +36,83 @@ import java.util.UUID;
 
 public class ContainerSettingCommand implements TabExecutor {
 
-    private final @NotNull LanguageManager lang;
+  private final @NotNull LanguageManager lang;
 
-    public ContainerSettingCommand(@NotNull LanguageManager lang) {
-        this.lang = lang;
+  public ContainerSettingCommand(@NotNull LanguageManager lang) {
+    this.lang = lang;
+  }
+
+  @Override
+  public boolean onCommand(
+      @NotNull CommandSender sender,
+      @NotNull Command command,
+      @NotNull String label,
+      @NotNull String[] args
+  ) {
+    if (!(sender instanceof Player player)) {
+      lang.sendMessage(sender, "messages.error.consoleUnsupported");
+      return true;
     }
 
-    @Override
-    public boolean onCommand(@NotNull CommandSender sender, @NotNull Command command, @NotNull String label, @NotNull String[] args) {
-        if (!(sender instanceof Player player)) {
-            lang.sendMessage(sender, "messages.error.consoleUnsupported");
-            return true;
-        }
+    PlayerToggle toggle = PlayerToggles.get(command.getName());
 
-        PlayerToggle toggle = PlayerToggles.get(command.getName());
-
-        // Shouldn't be possible.
-        if (toggle == null) {
-            JavaPlugin.getProvidingPlugin(getClass()).getLogger().warning("Command /" + command.getName() + " registered with no corresponding toggle!");
-            return false;
-        }
-
-        UUID playerId = player.getUniqueId();
-
-        if (args.length > 0) {
-            args[0] = args[0].toLowerCase(Locale.ENGLISH);
-
-            if (args[0].equals("on")) {
-                set(toggle, playerId, true);
-            } else if (args[0].equals("off")) {
-                set(toggle, playerId, false);
-            } else if (!args[0].equals("check")) {
-                // Invalid argument, show usage.
-                return false;
-            }
-
-        } else {
-            set(toggle, playerId, !toggle.is(playerId));
-        }
-
-        String onOff = lang.getLocalizedMessage(player, toggle.is(playerId) ? "messages.info.on" : "messages.info.off");
-        if (onOff == null) {
-            onOff = String.valueOf(toggle.is(playerId));
-        }
-
-        lang.sendMessage(
-                sender,
-                "messages.info.settingState",
-                new Replacement("%setting%", toggle.getName()),
-                new Replacement("%state%", onOff));
-
-        return true;
+    // Shouldn't be possible.
+    if (toggle == null) {
+      JavaPlugin.getProvidingPlugin(getClass()).getLogger().warning("Command /" + command.getName() + " registered with no corresponding toggle!");
+      return false;
     }
 
-    private void set(@NotNull PlayerToggle toggle, @NotNull UUID uuid, boolean state) {
-        if (toggle.set(uuid, state)) {
-            OpenEvents.notifyPlayerToggle(toggle, uuid, state);
-        }
+    UUID playerId = player.getUniqueId();
+
+    if (args.length > 0) {
+      args[0] = args[0].toLowerCase(Locale.ENGLISH);
+
+      if (args[0].equals("on")) {
+        set(toggle, playerId, true);
+      } else if (args[0].equals("off")) {
+        set(toggle, playerId, false);
+      } else if (!args[0].equals("check")) {
+        // Invalid argument, show usage.
+        return false;
+      }
+
+    } else {
+      set(toggle, playerId, !toggle.is(playerId));
     }
 
-    @Override
-    public List<String> onTabComplete(@NotNull CommandSender sender, @NotNull Command command, @NotNull String label, @NotNull String[] args) {
-        if (!command.testPermissionSilent(sender) || args.length != 1) {
-            return Collections.emptyList();
-        }
-
-        return TabCompleter.completeString(args[0], new String[] {"check", "on", "off"});
+    String onOff = lang.getLocalizedMessage(player, toggle.is(playerId) ? "messages.info.on" : "messages.info.off");
+    if (onOff == null) {
+      onOff = String.valueOf(toggle.is(playerId));
     }
 
+    lang.sendMessage(
+        sender,
+        "messages.info.settingState",
+        new Replacement("%setting%", toggle.getName()),
+        new Replacement("%state%", onOff)
+    );
+
+    return true;
+  }
+
+  private void set(@NotNull PlayerToggle toggle, @NotNull UUID uuid, boolean state) {
+    if (toggle.set(uuid, state)) {
+      OpenEvents.notifyPlayerToggle(toggle, uuid, state);
+    }
+  }
+
+  @Override
+  public List<String> onTabComplete(
+      @NotNull CommandSender sender,
+      @NotNull Command command,
+      @NotNull String label,
+      @NotNull String[] args
+  ) {
+    if (!command.testPermissionSilent(sender) || args.length != 1) {
+      return Collections.emptyList();
+    }
+
+    return TabCompleter.completeString(args[0], new String[]{"check", "on", "off"});
+  }
+
 }

plugin/src/main/java/com/lishid/openinv/command/OpenInvCommand.java

@@ -18,232 +18,161 @@ package com.lishid.openinv.command;
 
 import com.lishid.openinv.OpenInv;
 import com.lishid.openinv.internal.ISpecialInventory;
-import com.lishid.openinv.util.AccessEqualMode;
 import com.lishid.openinv.util.InventoryManager;
 import com.lishid.openinv.util.Permissions;
 import com.lishid.openinv.util.PlayerLoader;
-import com.lishid.openinv.util.TabCompleter;
 import com.lishid.openinv.util.config.Config;
 import com.lishid.openinv.util.lang.LanguageManager;
-import com.lishid.openinv.util.lang.Replacement;
 import org.bukkit.OfflinePlayer;
 import org.bukkit.command.Command;
 import org.bukkit.command.CommandSender;
 import org.bukkit.command.PluginCommand;
-import org.bukkit.command.TabExecutor;
 import org.bukkit.entity.Player;
-import org.bukkit.scheduler.BukkitRunnable;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
-import java.util.Collections;
-import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.StringJoiner;
+import java.util.WeakHashMap;
 import java.util.logging.Level;
 
-public class OpenInvCommand implements TabExecutor {
+public class OpenInvCommand extends PlayerLookupCommand {
 
-    private final @NotNull OpenInv plugin;
-    private final @NotNull Config config;
-    private final @NotNull InventoryManager manager;
-    private final @NotNull LanguageManager lang;
-    private final @NotNull PlayerLoader playerLoader;
-    private final HashMap<Player, String> openInvHistory = new HashMap<>();
-    private final HashMap<Player, String> openEnderHistory = new HashMap<>();
+  private final @NotNull InventoryManager manager;
+  private final Map<Player, String> openInvHistory = new WeakHashMap<>();
+  private final Map<Player, String> openEnderHistory = new WeakHashMap<>();
 
-    public OpenInvCommand(
-        @NotNull OpenInv plugin,
-        @NotNull Config config,
-        @NotNull InventoryManager manager,
-        @NotNull LanguageManager lang,
-        @NotNull PlayerLoader playerLoader) {
-        this.plugin = plugin;
-        this.config = config;
-        this.manager = manager;
-        this.lang = lang;
-        this.playerLoader = playerLoader;
+  public OpenInvCommand(
+      @NotNull OpenInv plugin,
+      @NotNull Config config,
+      @NotNull InventoryManager manager,
+      @NotNull LanguageManager lang,
+      @NotNull PlayerLoader playerLoader
+  ) {
+    super(plugin, lang, config, playerLoader);
+    this.manager = manager;
+  }
+
+  @Override
+  protected boolean isAccessInventory(@NotNull Command command) {
+    return command.getName().equals("openinv");
+  }
+
+  @Override
+  protected @Nullable String getTargetIdentifer(
+      @NotNull CommandSender sender,
+      @NotNull Command command,
+      @Nullable String argument,
+      boolean accessInv
+  ) {
+    // /openinv help
+    if (accessInv && argument != null && (argument.equalsIgnoreCase("help") || argument.equals("?"))) {
+      this.showHelp(sender);
+      return null;
     }
 
-    @Override
-    public boolean onCommand(@NotNull final CommandSender sender, @NotNull final Command command, @NotNull final String label, @NotNull final String[] args) {
-        boolean openInv = command.getName().equals("openinv");
+    // Command is player-only.
+    if (!(sender instanceof Player player)) {
+      lang.sendMessage(sender, "messages.error.consoleUnsupported");
+      return null;
+    }
 
-        if (openInv && args.length > 0 && (args[0].equalsIgnoreCase("help") || args[0].equals("?"))) {
-            this.showHelp(sender);
-            return true;
+    // Use fallthrough for no name provided.
+    if (argument == null) {
+      if (config.doesNoArgsOpenSelf()) {
+        return player.getUniqueId().toString();
+      }
+      return (accessInv ? this.openInvHistory : this.openEnderHistory)
+          .computeIfAbsent(player, localPlayer -> localPlayer.getUniqueId().toString());
+    }
+
+    if (!config.doesNoArgsOpenSelf()) {
+      // History management
+      (accessInv ? this.openInvHistory : this.openEnderHistory).put(player, argument);
+    }
+
+    return argument;
+  }
+
+  private void showHelp(@NotNull CommandSender sender) {
+    // Get registered commands
+    for (String commandName : plugin.getDescription().getCommands().keySet()) {
+      PluginCommand command = plugin.getCommand(commandName);
+
+      // Ensure command is successfully registered and sender can use it
+      if (command == null || !command.testPermissionSilent(sender)) {
+        continue;
+      }
+
+      // Send usage
+      sender.sendMessage(command.getUsage().replace("<command>", commandName));
+
+      List<String> aliases = command.getAliases();
+      if (!aliases.isEmpty()) {
+        // Assemble alias list
+        StringJoiner aliasJoiner = new StringJoiner(", ", "   (aliases: ", ")");
+        for (String alias : aliases) {
+          aliasJoiner.add(alias);
         }
 
-        if (!(sender instanceof Player player)) {
-            lang.sendMessage(sender, "messages.error.consoleUnsupported");
-            return true;
-        }
+        // Send all aliases
+        sender.sendMessage(aliasJoiner.toString());
+      }
 
-        String noArgValue;
-        if (config.doesNoArgsOpenSelf()) {
-            noArgValue = player.getUniqueId().toString();
-        } else {
-            // History management
-            noArgValue = (openInv ? this.openInvHistory : this.openEnderHistory).get(player);
+    }
+  }
 
-            if (noArgValue == null || noArgValue.isEmpty()) {
-                noArgValue = player.getUniqueId().toString();
-                (openInv ? this.openInvHistory : this.openEnderHistory).put(player, noArgValue);
-            }
-        }
-
-        final String name;
-
-        if (args.length < 1) {
-            name = noArgValue;
-        } else {
-            name = args[0];
-        }
-
-        new BukkitRunnable() {
-            @Override
-            public void run() {
-                final OfflinePlayer offlinePlayer = playerLoader.match(name);
-
-                if (offlinePlayer == null || (!offlinePlayer.hasPlayedBefore() && !offlinePlayer.isOnline())) {
-                    lang.sendMessage(player, "messages.error.invalidPlayer");
-                    return;
-                }
-
-                new BukkitRunnable() {
-                    @Override
-                    public void run() {
-                        if (!player.isOnline()) {
-                            return;
-                        }
-                        OpenInvCommand.this.openInventory(player, offlinePlayer, openInv);
-                    }
-                }.runTask(OpenInvCommand.this.plugin);
-
-            }
-        }.runTaskAsynchronously(this.plugin);
+  @Override
+  protected @Nullable OfflinePlayer getTarget(@NotNull String identifier) {
+    return playerLoader.match(identifier);
+  }
 
+  @Override
+  protected boolean deniedCommand(@NotNull CommandSender sender, @NotNull Player onlineTarget, boolean accessInv) {
+    if (onlineTarget.equals(sender)) {
+      // Permission for opening own inventory.
+      if (!(accessInv ? Permissions.INVENTORY_OPEN_SELF : Permissions.ENDERCHEST_OPEN_SELF).hasPermission(sender)) {
+        lang.sendMessage(sender, "messages.error.permissionOpenSelf");
         return true;
+
+      }
+    } else {
+      // Permission for opening others' inventories.
+      if (!(accessInv ? Permissions.INVENTORY_OPEN_OTHER : Permissions.ENDERCHEST_OPEN_OTHER).hasPermission(sender)) {
+        lang.sendMessage(sender, "messages.error.permissionOpenOther");
+        return true;
+      }
     }
 
-    private void showHelp(final CommandSender sender) {
-        // Get registered commands
-        for (String commandName : plugin.getDescription().getCommands().keySet()) {
-            PluginCommand command = plugin.getCommand(commandName);
+    return false;
+  }
 
-            // Ensure command is successfully registered and sender can use it
-            if (command == null  || !command.testPermissionSilent(sender)) {
-                continue;
-            }
-
-            // Send usage
-            sender.sendMessage(command.getUsage().replace("<command>", commandName));
-
-            List<String> aliases = command.getAliases();
-            if (!aliases.isEmpty()) {
-                // Assemble alias list
-                StringJoiner aliasJoiner = new StringJoiner(", ", "   (aliases: ", ")");
-                for (String alias : aliases) {
-                    aliasJoiner.add(alias);
-                }
-
-                // Send all aliases
-                sender.sendMessage(aliasJoiner.toString());
-            }
-
-        }
+  @Override
+  protected void handle(
+      @NotNull CommandSender sender,
+      @NotNull Player target,
+      boolean accessInv,
+      @NotNull String @NotNull [] args
+  ) {
+    Player player = (Player) sender;
+    if (!config.doesNoArgsOpenSelf()) {
+      // Record the target
+      (accessInv ? this.openInvHistory : this.openEnderHistory).put(player, target.getUniqueId().toString());
     }
 
-    private void openInventory(final Player player, final OfflinePlayer target, boolean openinv) {
-        Player onlineTarget;
-        boolean online = target.isOnline();
-
-        if (!online) {
-            if (!config.isOfflineDisabled() && Permissions.ACCESS_OFFLINE.hasPermission(player)) {
-                // Try loading the player's data
-                onlineTarget = playerLoader.load(target);
-            } else {
-                lang.sendMessage(player, "messages.error.permissionPlayerOffline");
-                return;
-            }
-        } else {
-            if (Permissions.ACCESS_ONLINE.hasPermission(player)) {
-                onlineTarget = target.getPlayer();
-            } else {
-                lang.sendMessage(player, "messages.error.permissionPlayerOnline");
-                return;
-            }
-        }
-
-        if (onlineTarget == null) {
-            lang.sendMessage(player, "messages.error.invalidPlayer");
-            return;
-        }
-
-        // Permissions checks
-        if (onlineTarget.equals(player)) {
-            // Permission for opening own inventory.
-            if (!(openinv ? Permissions.INVENTORY_OPEN_SELF : Permissions.ENDERCHEST_OPEN_SELF).hasPermission(player)) {
-                lang.sendMessage(player, "messages.error.permissionOpenSelf");
-                return;
-
-            }
-        } else {
-            // Permission for opening others' inventories.
-            if (!(openinv ? Permissions.INVENTORY_OPEN_OTHER : Permissions.ENDERCHEST_OPEN_OTHER).hasPermission(player)) {
-                lang.sendMessage(player, "messages.error.permissionOpenOther");
-                return;
-            }
-
-            // Protected check
-            for (int level = 4; level > 0; --level) {
-                String permission = "openinv.access.level." + level;
-                if (onlineTarget.hasPermission(permission)
-                        && (!player.hasPermission(permission) || config.getAccessEqualMode() == AccessEqualMode.DENY)) {
-                    lang.sendMessage(
-                        player,
-                        "messages.error.permissionExempt",
-                        new Replacement("%target%", onlineTarget.getDisplayName()));
-                    return;
-                }
-            }
-
-            // Crossworld check
-            if (!Permissions.ACCESS_CROSSWORLD.hasPermission(player)
-                    && !onlineTarget.getWorld().equals(player.getWorld())) {
-                lang.sendMessage(
-                        player,
-                        "messages.error.permissionCrossWorld",
-                        new Replacement("%target%", onlineTarget.getDisplayName()));
-                return;
-            }
-        }
-
-        if (!config.doesNoArgsOpenSelf()) {
-            // Record the target
-            (openinv ? this.openInvHistory : this.openEnderHistory).put(player, target.getUniqueId().toString());
-        }
-
-        // Create the inventory
-        final ISpecialInventory inv;
-        try {
-            inv = openinv ? manager.getInventory(onlineTarget) : manager.getEnderChest(onlineTarget);
-        } catch (Exception e) {
-            lang.sendMessage(player, "messages.error.commandException");
-            plugin.getLogger().log(Level.WARNING, "Unable to create ISpecialInventory", e);
-            return;
-        }
-
-        // Open the inventory
-        plugin.openInventory(player, inv);
+    // Create the inventory
+    final ISpecialInventory inv;
+    try {
+      inv = accessInv ? manager.getInventory(target) : manager.getEnderChest(target);
+    } catch (Exception e) {
+      lang.sendMessage(player, "messages.error.commandException");
+      plugin.getLogger().log(Level.WARNING, "Unable to create ISpecialInventory", e);
+      return;
     }
 
-    @Override
-    public List<String> onTabComplete(@NotNull CommandSender sender, @NotNull Command command, @NotNull String label, @NotNull String[] args) {
-        if (!command.testPermissionSilent(sender) || args.length != 1) {
-            return Collections.emptyList();
-        }
-
-        return TabCompleter.completeOnlinePlayer(sender, args[0]);
-    }
+    // Open the inventory
+    plugin.openInventory(player, inv);
+  }
 
 }