Bump version to 5.1.9 for release

The weird part is that I don't have any of these problems locally. Remote is executing tasks in a really weird order, common adapter is building after Spigot adapter despite Spigot adapter depending on an output from it.
May just have to disable caching, but would like to avoid that if possible.

.github/dependabot.yml

@@ -4,7 +4,7 @@ updates:
     directory: "/"
     schedule:
       interval: "monthly"
-  - package-ecosystem: "maven"
+  - package-ecosystem: "gradle"
     directory: "/"
     schedule:
       interval: "monthly"

.github/workflows/ci.yml

@@ -29,7 +29,7 @@ jobs:
       - uses: gradle/actions/setup-gradle@v4
 
       - name: Build with Gradle
-        run: ./gradlew build
+        run: ./gradlew clean build
 
       # Upload artifacts
       - name: Upload Distributable Jar

build.gradle.kts

@@ -4,6 +4,9 @@ plugins {
   alias(libs.plugins.shadow) apply false
 }
 
+// Set by Spigot module, used by Paper module to convert to Spigot's version of Mojang mappings.
+project.ext.set("craftbukkitPackage", "UNKNOWN")
+
 repositories {
   maven("https://repo.papermc.io/repository/maven-public/")
 }

buildSrc/src/main/kotlin/ReobfTask.kt

@@ -0,0 +1,60 @@
+import org.gradle.api.file.RegularFile
+import org.gradle.api.provider.Property
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.InputFile
+import org.gradle.api.tasks.TaskAction
+import org.gradle.api.tasks.bundling.Jar
+import java.io.File
+import java.nio.file.Path
+import java.nio.file.Paths
+
+abstract class ReobfTask: Jar() {
+
+  @get:Input
+  open val spigotVersion: Property<String> = objectFactory.property(String::class.java)
+
+  @get:InputFile
+  open val inputFile: Property<RegularFile> = objectFactory.fileProperty()
+
+  @get:Input
+  open val intermediaryClassifier: Property<String> = objectFactory.property(String::class.java).convention("mojang-mapped")
+
+  init {
+    archiveClassifier.convention("reobf")
+  }
+
+  @TaskAction
+  override fun copy() {
+    val spigotVer = spigotVersion.get()
+    val inFile = inputFile.get().asFile
+    val obfPath = inFile.resolveSibling(inFile.name.replace(".jar", "-${intermediaryClassifier.get()}.jar"))
+
+    // https://www.spigotmc.org/threads/510208/#post-4184317
+    val specialsource = project.configurations.named("spigotRemap").get().incoming.artifacts.artifacts
+      .first { it.id.componentIdentifier.toString() == "net.md-5:SpecialSource:1.11.4" }.file.path
+    val repo = Paths.get(project.repositories.mavenLocal().url)
+    val spigotDir = repo.resolve("org/spigotmc/spigot/$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-$spigotVer-maps-mojang.txt")
+    remapPartial(specialsource, mojangServer, mojangMappings, inFile, obfPath, true)
+
+    // Remap obfuscated intermediary jar to Spigot and replace original
+    val obfServer = spigotDir.resolve("spigot-$spigotVer-remapped-obf.jar")
+    val spigotMappings = mappingDir.resolve("minecraft-server-$spigotVer-maps-spigot.csrg")
+    remapPartial(specialsource, obfServer, spigotMappings, obfPath, archiveFile.get().asFile, false)
+  }
+
+  private fun remapPartial(specialSource: String, serverJar: Path, mapping: Path, input: File, output: File, reverse: Boolean) {
+    project.providers.exec {
+      commandLine("java", "-cp", "$specialSource${File.pathSeparator}$serverJar",
+        "net.md_5.specialsource.SpecialSource", "--live",
+        "-i", input.path, "-o", output.path,
+        "-m", "$mapping",
+        if (reverse) "--reverse" else "")
+    }.result.get()
+  }
+
+}

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()
-  }
-}

gradle.properties

@@ -1,7 +1,7 @@
 # Project meta
-group = com.lishid.openinv
-version = 5.1.7
-description = A Bukkit plugin for opening normally-inaccessible inventories.
+group=com.lishid.openinv
+version=5.1.9
+description=A Bukkit plugin for opening normally-inaccessible inventories.
 
 # Gradle configuration
 org.gradle.parallel=true

gradle/libs.versions.toml

@@ -1,15 +1,13 @@
 [versions]
 spigotapi = "1.21.4-R0.1-SNAPSHOT"
-spigot = "1.21.4-R0.1-SNAPSHOT"
 specialsource = "1.11.4"
 planarwrappers = "3.3.0"
 annotations = "26.0.2"
 paperweight = "2.0.0-beta.14"
-shadow = "8.3.5"
+shadow = "8.3.6"
 
 [libraries]
 spigotapi = { module = "org.spigotmc:spigot-api", version.ref = "spigotapi" }
-spigot = { module = "org.spigotmc:spigot", version.ref = "spigot" }
 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" }

internal/common/build.gradle.kts

@@ -5,6 +5,16 @@ plugins {
   alias(libs.plugins.paperweight)
 }
 
+//tasks {
+//  withType<JavaCompile> {
+//    // OpenPlayer unchecked warning is due to superclass' messy inheritance and legacy methods.
+//    options.compilerArgs.add("-Xlint:unchecked")
+//    // PlayerManager uses "deprecated" method matching vanilla to support legacy save data.
+//    // While vanilla still feels that it is appropriate to use in the load process, we will too.
+//    options.compilerArgs.add("-Xlint:deprecation")
+//  }
+//}
+
 configurations.all {
   resolutionStrategy.capabilitiesResolution.withCapability("org.spigotmc:spigot-api") {
     val paper = candidates.firstOrNull {
@@ -30,8 +40,7 @@ val spigot = tasks.register<ShadowJar>("spigotRelocations") {
   dependsOn(tasks.jar)
   from(sourceSets.main.get().output)
   relocate("com.lishid.openinv.internal.common", "com.lishid.openinv.internal.reobf")
-  // TODO pass from Spigot adapter somehow. Can tasks be added by another project? Can we fetch a global config?
-  relocate("org.bukkit.craftbukkit", "org.bukkit.craftbukkit.v1_21_R3")
+  relocate("org.bukkit.craftbukkit", "org.bukkit.craftbukkit.${rootProject.extra["craftbukkitPackage"]}")
   archiveClassifier = "spigot"
 }
 

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

@@ -8,7 +8,7 @@ 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.common.container.OpenInventory;
-import com.lishid.openinv.internal.common.container.Placeholders;
+import com.lishid.openinv.internal.common.container.slot.placeholder.PlaceholderLoader;
 import com.lishid.openinv.internal.common.player.PlayerManager;
 import com.lishid.openinv.util.lang.LanguageManager;
 import net.minecraft.world.Container;
@@ -24,7 +24,7 @@ import java.util.logging.Logger;
 
 public class InternalAccessor implements Accessor {
 
-  private final @NotNull Logger logger;
+  protected final @NotNull Logger logger;
   private final @NotNull PlayerManager manager;
   private final @NotNull AnySilentContainer anySilentContainer;
 
@@ -69,12 +69,11 @@ public class InternalAccessor implements Accessor {
   @Override
   public void reload(@NotNull ConfigurationSection config) {
     ConfigurationSection placeholders = config.getConfigurationSection("placeholders");
-    if (placeholders != null) {
-      try {
-        Placeholders.load(placeholders);
-      } catch (Exception e) {
-        logger.log(Level.WARNING, "Caught exception loading placeholder overrides!", e);
-      }
+    try {
+      // Reset placeholders to defaults and try to load configuration.
+      new PlaceholderLoader().load(placeholders);
+    } catch (Exception e) {
+      logger.log(Level.WARNING, "Caught exception loading placeholder overrides!", e);
     }
   }
 

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

@@ -14,6 +14,7 @@ import com.lishid.openinv.internal.common.container.slot.ContentList;
 import com.lishid.openinv.internal.common.container.slot.ContentOffHand;
 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 net.minecraft.ChatFormatting;
 import net.minecraft.core.NonNullList;
@@ -191,12 +192,16 @@ public class OpenInventory implements Container, InternalOwned<ServerPlayer>, IS
           };
         }
       });
-      slots.set(startIndex + 11, new ContentCraftingResult(owner));
+      slots.set(startIndex + 11, getCraftingResult(owner));
     }
 
     return startIndex + listSize;
   }
 
+  protected Content getCraftingResult(@NotNull ServerPlayer serverPlayer) {
+    return new ContentCraftingResult(serverPlayer);
+  }
+
   public Slot getMenuSlot(int index, int x, int y) {
     return slots.get(index).asSlot(this, index, x, y);
   }

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

@@ -62,7 +62,7 @@ public class OpenDummyInventory extends CraftInventory implements ViewOnly {
   }
 
   @Override
-  public ItemStack[] getContents() {
+  public ItemStack @NotNull [] getContents() {
     return new ItemStack[getSize()];
   }
 
@@ -72,7 +72,7 @@ public class OpenDummyInventory extends CraftInventory implements ViewOnly {
   }
 
   @Override
-  public @NotNull ItemStack[] getStorageContents() {
+  public @NotNull ItemStack @NotNull [] getStorageContents() {
     return new ItemStack[getSize()];
   }
 

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

@@ -111,11 +111,13 @@ public class OpenDummyPlayerInventory extends OpenDummyInventory implements Play
 
   }
 
+  @Deprecated
   @Override
   public @NotNull ItemStack getItemInHand() {
     return new ItemStack(Material.AIR);
   }
 
+  @Deprecated
   @Override
   public void setItemInHand(@Nullable ItemStack stack) {
 

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

@@ -170,11 +170,13 @@ public class OpenPlayerInventory extends CraftInventory implements PlayerInvento
     getInventory().getOwnerHandle().getInventory().offhand.set(0, CraftItemStack.asNMSCopy(item));
   }
 
+  @Deprecated
   @Override
   public @NotNull ItemStack getItemInHand() {
     return getItemInMainHand();
   }
 
+  @Deprecated
   @Override
   public void setItemInHand(@Nullable ItemStack stack) {
     setItemInMainHand(stack);

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

@@ -1,6 +1,6 @@
 package com.lishid.openinv.internal.common.container.slot;
 
-import com.lishid.openinv.internal.common.container.Placeholders;
+import com.lishid.openinv.internal.common.container.slot.placeholder.Placeholders;
 import com.lishid.openinv.internal.common.player.OpenPlayer;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.Container;
@@ -31,7 +31,7 @@ public class ContentCrafting implements Content {
     return isAvailable(holder);
   }
 
-  static boolean isAvailable(@NotNull ServerPlayer holder) {
+  public static boolean isAvailable(@NotNull ServerPlayer holder) {
     // 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.

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

@@ -1,6 +1,6 @@
 package com.lishid.openinv.internal.common.container.slot;
 
-import com.lishid.openinv.internal.common.container.Placeholders;
+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.inventory.InventoryMenu;

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

@@ -1,6 +1,6 @@
 package com.lishid.openinv.internal.common.container.slot;
 
-import com.lishid.openinv.internal.common.container.Placeholders;
+import com.lishid.openinv.internal.common.container.slot.placeholder.Placeholders;
 import com.lishid.openinv.internal.common.player.OpenPlayer;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.Container;

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

@@ -1,6 +1,6 @@
 package com.lishid.openinv.internal.common.container.slot;
 
-import com.lishid.openinv.internal.common.container.Placeholders;
+import com.lishid.openinv.internal.common.container.slot.placeholder.Placeholders;
 import com.lishid.openinv.internal.common.player.OpenPlayer;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.Container;

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

@@ -1,6 +1,6 @@
 package com.lishid.openinv.internal.common.container.slot;
 
-import com.lishid.openinv.internal.common.container.Placeholders;
+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;

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

@@ -12,7 +12,7 @@ import org.jetbrains.annotations.NotNull;
  */
 public class ContentViewOnly implements Content {
 
-  @NotNull ServerPlayer holder;
+  protected @NotNull ServerPlayer holder;
 
   public ContentViewOnly(@NotNull ServerPlayer holder) {
     this.holder = holder;

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

@@ -1,6 +1,6 @@
 package com.lishid.openinv.internal.common.container.slot;
 
-import com.lishid.openinv.internal.common.container.Placeholders;
+import com.lishid.openinv.internal.common.container.slot.placeholder.Placeholders;
 import net.minecraft.world.Container;
 import net.minecraft.world.entity.player.Player;
 import net.minecraft.world.inventory.Slot;

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

@@ -0,0 +1,18 @@
+package com.lishid.openinv.internal.common.container.slot.placeholder;
+
+import net.minecraft.core.component.DataComponents;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.component.CustomModelData;
+
+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());
+
+  @Override
+  protected void addModelData(ItemStack itemStack) {
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+  }
+
+}

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

@@ -1,6 +1,5 @@
-package com.lishid.openinv.internal.common.container;
+package com.lishid.openinv.internal.common.container.slot.placeholder;
 
-import com.lishid.openinv.internal.common.player.OpenPlayer;
 import net.minecraft.core.Registry;
 import net.minecraft.core.RegistryAccess;
 import net.minecraft.core.component.DataComponents;
@@ -8,12 +7,10 @@ import net.minecraft.core.registries.Registries;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.nbt.TagParser;
 import net.minecraft.network.chat.Component;
-import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.util.Unit;
 import net.minecraft.world.item.DyeColor;
 import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.item.Items;
-import net.minecraft.world.item.component.CustomModelData;
 import net.minecraft.world.item.component.DyedItemColor;
 import net.minecraft.world.level.GameType;
 import net.minecraft.world.level.ItemLike;
@@ -23,56 +20,57 @@ import net.minecraft.world.level.block.entity.BannerPatterns;
 import org.bukkit.configuration.ConfigurationSection;
 import org.bukkit.craftbukkit.CraftRegistry;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
-import java.util.EnumMap;
 import java.util.List;
 import java.util.Optional;
 
-public final class Placeholders {
+public abstract class PlaceholderLoaderBase {
 
-  private static final CustomModelData DEFAULT_CUSTOM_MODEL_DATA = new CustomModelData(List.of(), List.of(), List.of("openinv:custom"), List.of());
-  public static final @NotNull EnumMap<GameType, ItemStack> BLOCKED_GAME_TYPE = new EnumMap<>(GameType.class);
-  public static @NotNull ItemStack craftingOutput = defaultCraftingOutput();
-  public static @NotNull ItemStack cursor = defaultCursor();
-  public static @NotNull ItemStack drop = defaultDrop();
-  public static @NotNull ItemStack emptyHelmet = getEmptyArmor(Items.LEATHER_HELMET);
-  public static @NotNull ItemStack emptyChestplate = getEmptyArmor(Items.LEATHER_CHESTPLATE);
-  public static @NotNull ItemStack emptyLeggings = getEmptyArmor(Items.LEATHER_LEGGINGS);
-  public static @NotNull ItemStack emptyBoots = getEmptyArmor(Items.LEATHER_BOOTS);
-  public static @NotNull ItemStack emptyOffHand = getEmptyShield();
-  public static @NotNull ItemStack notSlot = defaultNotSlot();
-  public static @NotNull ItemStack blockedOffline = defaultBlockedOffline();
-
-  static {
+  protected PlaceholderLoaderBase() {
     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()));
-      BLOCKED_GAME_TYPE.put(type, typeItem);
+      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 static void load(@NotNull ConfigurationSection section) throws Exception {
-    craftingOutput = parse(section, "crafting-output", craftingOutput);
-    cursor = parse(section, "cursor", cursor);
-    drop = parse(section, "drop", drop);
-    emptyHelmet = parse(section, "empty-helmet", emptyHelmet);
-    emptyChestplate = parse(section, "empty-chestplate", emptyChestplate);
-    emptyLeggings = parse(section, "empty-leggings", emptyLeggings);
-    emptyBoots = parse(section, "empty-boots", emptyBoots);
-    emptyOffHand = parse(section, "empty-off-hand", emptyOffHand);
-    notSlot = parse(section, "not-a-slot", notSlot);
-    blockedOffline = parse(section, "blocked.offline", blockedOffline);
-    BLOCKED_GAME_TYPE.put(GameType.CREATIVE, parse(section, "blocked.creative", BLOCKED_GAME_TYPE.get(GameType.CREATIVE)));
-    BLOCKED_GAME_TYPE.put(GameType.SPECTATOR, parse(section, "blocked.spectator", BLOCKED_GAME_TYPE.get(GameType.SPECTATOR)));
+  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(
-      @NotNull ConfigurationSection section,
+      @Nullable ConfigurationSection section,
       @NotNull String path,
       @NotNull ItemStack defaultStack) throws Exception {
+    if (section == null) {
+      return defaultStack;
+    }
+
     String itemText = section.getString(path);
 
     if (itemText == null) {
@@ -84,23 +82,17 @@ public final class Placeholders {
     return parsed.filter(itemStack -> !itemStack.isEmpty()).orElse(defaultStack);
   }
 
-  public static ItemStack survivalOnly(@NotNull ServerPlayer serverPlayer) {
-    if (!OpenPlayer.isConnected(serverPlayer.connection)) {
-      return blockedOffline;
-    }
+  protected abstract void addModelData(ItemStack itemStack);
 
-    return BLOCKED_GAME_TYPE.getOrDefault(serverPlayer.gameMode.getGameModeForPlayer(), ItemStack.EMPTY);
-  }
-
-  private static ItemStack defaultCraftingOutput() {
+  protected @NotNull ItemStack defaultCraftingOutput() {
     // Crafting table: "Crafting"
     ItemStack itemStack = new ItemStack(Items.CRAFTING_TABLE);
     itemStack.set(DataComponents.ITEM_NAME, Component.translatable("container.crafting"));
-    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    addModelData(itemStack);
     return itemStack;
   }
 
-  private static ItemStack defaultCursor() {
+  protected @NotNull ItemStack defaultCursor() {
     // Cursor-like banner with no tooltip
     ItemStack itemStack = new ItemStack(Items.WHITE_BANNER);
     RegistryAccess minecraftRegistry = CraftRegistry.getMinecraftRegistry();
@@ -113,31 +105,32 @@ public final class Placeholders {
             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.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    addModelData(itemStack);
     itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
     return itemStack;
   }
 
-  private static ItemStack defaultDrop() {
+  protected @NotNull ItemStack defaultDrop() {
     // Dropper: "Drop Selected Item"
     ItemStack itemStack = new ItemStack(Items.DROPPER);
     // Note: translatable component, not keybind component! We want the text identifying the keybind, not the key.
     itemStack.set(DataComponents.ITEM_NAME, Component.translatable("key.drop"));
-    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    addModelData(itemStack);
     return itemStack;
   }
 
-  private static ItemStack getEmptyArmor(ItemLike item) {
+  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);
     itemStack.set(DataComponents.DYED_COLOR, color);
     itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
-    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    addModelData(itemStack);
     return itemStack;
   }
 
-  private static ItemStack getEmptyShield() {
+  protected @NotNull ItemStack defaultShield() {
+    // Shield with "missing texture" pattern, magenta and black squares.
     ItemStack itemStack = new ItemStack(Items.SHIELD);
     itemStack.set(DataComponents.BASE_COLOR, DyeColor.MAGENTA);
     RegistryAccess minecraftRegistry = CraftRegistry.getMinecraftRegistry();
@@ -155,19 +148,19 @@ public final class Placeholders {
             new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(topRight), DyeColor.BLACK),
             new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(bottomRight), DyeColor.BLACK))));
     itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
-    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    addModelData(itemStack);
     return itemStack;
   }
 
-  private static ItemStack defaultNotSlot() {
+  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);
-    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    addModelData(itemStack);
     return itemStack;
   }
 
-  private static ItemStack defaultBlockedOffline() {
+  protected @NotNull ItemStack defaultBlockedOffline() {
     // Barrier: "Not available - Offline"
     ItemStack itemStack = new ItemStack(Items.BARRIER);
     itemStack.set(DataComponents.ITEM_NAME,
@@ -177,8 +170,4 @@ public final class Placeholders {
     return itemStack;
   }
 
-  private Placeholders() {
-    throw new IllegalStateException("Cannot create instance of utility class.");
-  }
-
 }

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

@@ -0,0 +1,37 @@
+package com.lishid.openinv.internal.common.container.slot.placeholder;
+
+import com.lishid.openinv.internal.common.player.OpenPlayer;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.GameType;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.EnumMap;
+
+public final class Placeholders {
+
+  static final @NotNull EnumMap<GameType, ItemStack> BLOCKED_GAME_TYPE = new EnumMap<>(GameType.class);
+  public static @NotNull ItemStack craftingOutput = ItemStack.EMPTY;
+  public static @NotNull ItemStack cursor = ItemStack.EMPTY;
+  public static @NotNull ItemStack drop = ItemStack.EMPTY;
+  public static @NotNull ItemStack emptyHelmet = ItemStack.EMPTY;
+  public static @NotNull ItemStack emptyChestplate = ItemStack.EMPTY;
+  public static @NotNull ItemStack emptyLeggings = ItemStack.EMPTY;
+  public static @NotNull ItemStack emptyBoots = ItemStack.EMPTY;
+  public static @NotNull ItemStack emptyOffHand = ItemStack.EMPTY;
+  public static @NotNull ItemStack notSlot = ItemStack.EMPTY;
+  public static @NotNull ItemStack blockedOffline = ItemStack.EMPTY;
+
+  public static ItemStack survivalOnly(@NotNull ServerPlayer serverPlayer) {
+    if (!OpenPlayer.isConnected(serverPlayer.connection)) {
+      return blockedOffline;
+    }
+
+    return BLOCKED_GAME_TYPE.getOrDefault(serverPlayer.gameMode.getGameModeForPlayer(), ItemStack.EMPTY);
+  }
+
+  private Placeholders() {
+    throw new IllegalStateException("Cannot create instance of utility class.");
+  }
+
+}

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

@@ -5,6 +5,7 @@ import com.lishid.openinv.internal.common.container.OpenEnderChest;
 import com.lishid.openinv.internal.common.container.OpenInventory;
 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;
@@ -38,18 +39,7 @@ import java.util.logging.Logger;
 
 public class PlayerManager implements com.lishid.openinv.internal.PlayerManager {
 
-  private static boolean paper;
-
-  static {
-    try {
-      Class.forName("io.papermc.paper.configuration.Configuration");
-      paper = true;
-    } catch (ClassNotFoundException ignored) {
-      paper = false;
-    }
-  }
-
-  private final @NotNull Logger logger;
+  protected final @NotNull Logger logger;
   private @Nullable Field bukkitEntity;
 
   public PlayerManager(@NotNull Logger logger) {
@@ -107,7 +97,7 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
     return null;
   }
 
-  private @NotNull ServerPlayer createNewPlayer(
+  protected @NotNull ServerPlayer createNewPlayer(
       @NotNull MinecraftServer server,
       @NotNull ServerLevel worldServer,
       @NotNull final OfflinePlayer offline) {
@@ -158,10 +148,8 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
     // Game type settings are also loaded separately.
     player.loadGameTypes(loadedData);
 
-    if (paper) {
-      // Paper: world is not loaded by ServerPlayer#load(CompoundTag).
-      parseWorld(player, loadedData);
-    }
+    // World is not loaded by ServerPlayer#load(CompoundTag) on Paper.
+    parseWorld(player, loadedData);
 
     return true;
   }
@@ -200,7 +188,7 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
     }
   }
 
-  private void injectPlayer(ServerPlayer player) throws IllegalAccessException {
+  protected void injectPlayer(ServerPlayer player) throws IllegalAccessException {
     if (bukkitEntity == null) {
       return;
     }
@@ -259,15 +247,21 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
     // resulting in a title change but no other state modifications (like cursor position).
     menu.setTitle(title);
 
-    menu = CraftEventFactory.callInventoryOpenEvent(player, menu, false);
+    var pair = CraftEventFactory.callInventoryOpenEventWithTitle(player, menu);
+    menu = pair.getSecond();
 
     // Menu is null if event is cancelled.
     if (menu == null) {
       return null;
     }
 
+    var newTitle = pair.getFirst();
+    if (newTitle != null) {
+      title = PaperAdventure.asVanilla(newTitle);
+    }
+
     player.containerMenu = menu;
-    player.connection.send(new ClientboundOpenScreenPacket(menu.containerId, menu.getType(), menu.getTitle()));
+    player.connection.send(new ClientboundOpenScreenPacket(menu.containerId, menu.getType(), title));
     player.initMenu(menu);
 
     return menu.getBukkitView();

internal/paper1_21_1/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_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

@@ -0,0 +1,80 @@
+package com.lishid.openinv.internal.paper1_21_1;
+
+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.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.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 {
+
+  private 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;
+    this.manager = new PlayerManager(logger);
+    this.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 PlaceholderLoader().load(placeholders);
+    } catch (Exception e) {
+      logger.log(Level.WARNING, "Caught exception loading placeholder overrides!", e);
+    }
+  }
+
+}

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

@@ -0,0 +1,20 @@
+package com.lishid.openinv.internal.paper1_21_1.container;
+
+import com.lishid.openinv.internal.common.container.slot.Content;
+import com.lishid.openinv.internal.paper1_21_1.container.slot.ContentCraftingResult;
+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 OpenInventory(@NotNull Player bukkitPlayer) {
+    super(bukkitPlayer);
+  }
+
+  @Override
+  protected Content getCraftingResult(@NotNull ServerPlayer serverPlayer) {
+    return new ContentCraftingResult(serverPlayer);
+  }
+
+}

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

@@ -0,0 +1,46 @@
+package com.lishid.openinv.internal.paper1_21_1.container.slot;
+
+import com.lishid.openinv.internal.common.container.slot.ContentCrafting;
+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 net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.inventory.InventoryMenu;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+public class ContentCraftingResult extends ContentViewOnly {
+
+  public ContentCraftingResult(@NotNull ServerPlayer holder) {
+    super(holder);
+  }
+
+  @Override
+  public ItemStack get() {
+    InventoryMenu inventoryMenu = holder.inventoryMenu;
+    return inventoryMenu.getSlot(inventoryMenu.getResultSlotIndex()).getItem();
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotViewOnly(container, slot, x, y) {
+      @Override
+      public ItemStack getOrDefault() {
+        if (!ContentCrafting.isAvailable(holder)) {
+          return Placeholders.survivalOnly(holder);
+        }
+        InventoryMenu inventoryMenu = holder.inventoryMenu;
+        return inventoryMenu.getSlot(inventoryMenu.getResultSlotIndex()).getItem();
+      }
+    };
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return InventoryType.SlotType.RESULT;
+  }
+
+}

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

@@ -0,0 +1,65 @@
+package com.lishid.openinv.internal.paper1_21_1.container.slot.placeholder;
+
+import com.lishid.openinv.internal.paper1_21_3.container.slot.placeholder.NumericDataPlaceholderLoader;
+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 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 PlaceholderLoader extends NumericDataPlaceholderLoader {
+
+  @Override
+  protected @NotNull ItemStack defaultCursor() {
+    // Cursor-like banner with no tooltip
+    ItemStack itemStack = new ItemStack(Items.WHITE_BANNER);
+    RegistryAccess minecraftRegistry = CraftRegistry.getMinecraftRegistry();
+    Registry<BannerPattern> bannerPatterns = minecraftRegistry.registryOrThrow(Registries.BANNER_PATTERN);
+    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))));
+    addModelData(itemStack);
+    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+    return itemStack;
+  }
+
+  @Override
+  protected @NotNull ItemStack defaultShield() {
+    // Shield with "missing texture" pattern, magenta and black squares.
+    ItemStack itemStack = new ItemStack(Items.SHIELD);
+    itemStack.set(DataComponents.BASE_COLOR, DyeColor.MAGENTA);
+    RegistryAccess minecraftRegistry = CraftRegistry.getMinecraftRegistry();
+    Registry<BannerPattern> bannerPatterns = minecraftRegistry.registryOrThrow(Registries.BANNER_PATTERN);
+    BannerPattern halfLeft = bannerPatterns.getOrThrow(BannerPatterns.HALF_VERTICAL);
+    BannerPattern topLeft = bannerPatterns.getOrThrow(BannerPatterns.SQUARE_TOP_LEFT);
+    BannerPattern topRight = bannerPatterns.getOrThrow(BannerPatterns.SQUARE_TOP_RIGHT);
+    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))));
+    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

@@ -0,0 +1,54 @@
+package com.lishid.openinv.internal.paper1_21_1.player;
+
+import com.mojang.authlib.GameProfile;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ClientInformation;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.player.ChatVisiblity;
+import org.bukkit.OfflinePlayer;
+import org.jetbrains.annotations.NotNull;
+
+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 @NotNull ServerPlayer createNewPlayer(
+      @NotNull MinecraftServer server,
+      @NotNull ServerLevel worldServer,
+      @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());
+
+    ClientInformation dummyInfo = new ClientInformation(
+        "en_us",
+        1, // Reduce distance just in case.
+        ChatVisiblity.HIDDEN, // Don't accept chat.
+        false,
+        ServerPlayer.DEFAULT_MODEL_CUSTOMIZATION,
+        ServerPlayer.DEFAULT_MAIN_HAND,
+        true,
+        false // Don't list in player list (not that this player is in the list anyway).
+    );
+
+    ServerPlayer entity = new ServerPlayer(server, worldServer, profile, dummyInfo);
+
+    try {
+      injectPlayer(entity);
+    } catch (IllegalAccessException e) {
+      logger.log(
+          java.util.logging.Level.WARNING,
+          e,
+          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!");
+    }
+
+    return entity;
+  }
+
+}

internal/paper1_21_3/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("1.21.3-R0.1-SNAPSHOT")
+}

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

@@ -0,0 +1,28 @@
+package com.lishid.openinv.internal.paper1_21_3;
+
+import com.lishid.openinv.internal.paper1_21_3.container.slot.placeholder.NumericDataPlaceholderLoader;
+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 {
+
+  public InternalAccessor(@NotNull Logger logger, @NotNull LanguageManager lang) {
+    super(logger, lang);
+  }
+
+  @Override
+  public void reload(@NotNull ConfigurationSection config) {
+    ConfigurationSection placeholders = config.getConfigurationSection("placeholders");
+    try {
+      // Reset placeholders to defaults and try to load configuration.
+      new NumericDataPlaceholderLoader().load(placeholders);
+    } catch (Exception e) {
+      logger.log(Level.WARNING, "Caught exception loading placeholder overrides!", e);
+    }
+  }
+
+}

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

@@ -0,0 +1,31 @@
+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 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 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);
+  }
+
+}

internal/spigot/build.gradle.kts

@@ -1,5 +1,4 @@
 plugins {
-  `remap-spigot`
   `openinv-base`
   alias(libs.plugins.shadow)
 }
@@ -8,6 +7,10 @@ repositories {
   mavenLocal()
 }
 
+val spigotVer = "1.21.4-R0.1-SNAPSHOT"
+rootProject.extra["spigotVersion"] = spigotVer
+rootProject.extra["craftbukkitPackage"] = "v1_21_R3"
+
 configurations.all {
   resolutionStrategy.capabilitiesResolution.withCapability("org.spigotmc:spigot-api") {
     val spigot = candidates.firstOrNull {
@@ -22,9 +25,12 @@ configurations.all {
   }
 }
 
+val spigotRemap = configurations.create("spigotRemap")
+
 dependencies {
+  spigotRemap("net.md-5:SpecialSource:1.11.4:shaded")
   compileOnly(libs.spigotapi)
-  compileOnly(variantOf(libs.spigot) { classifier("remapped-mojang") })
+  compileOnly(create("org.spigotmc", "spigot", spigotVer, classifier = "remapped-mojang"))
 
   compileOnly(project(":openinvapi"))
   compileOnly(project(":openinvcommon"))
@@ -37,11 +43,24 @@ 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") {
+val reobfTask = tasks.register<ReobfTask>("reobfTask") {
   notCompatibleWithConfigurationCache("gradle is hard")
   dependsOn(tasks.shadowJar)
-  inputs.files(tasks.shadowJar.get().outputs.files.files)
-  spigotVersion = libs.spigot.get().version.toString()
+  inputFile.value(tasks.shadowJar.get().archiveFile.get())
+  spigotVersion.value(spigotVer)
+}
+
+configurations {
+  consumable("reobf") {
+    attributes {
+      attribute(Category.CATEGORY_ATTRIBUTE, objects.named(Category.LIBRARY))
+      attribute(Usage.USAGE_ATTRIBUTE, objects.named(Usage.JAVA_RUNTIME))
+      attribute(Bundling.BUNDLING_ATTRIBUTE, objects.named(Bundling.EXTERNAL))
+      attribute(LibraryElements.LIBRARY_ELEMENTS_ATTRIBUTE, objects.named(LibraryElements.JAR))
+    }
+  }
+}
+
+artifacts {
+  add("reobf", reobfTask)
 }

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

@@ -4,9 +4,7 @@ import com.lishid.openinv.internal.ISpecialInventory;
 import com.lishid.openinv.internal.reobf.container.OpenEnderChest;
 import com.lishid.openinv.internal.reobf.container.OpenInventory;
 import com.mojang.authlib.GameProfile;
-import com.mojang.serialization.Dynamic;
 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;
@@ -18,13 +16,10 @@ 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 org.bukkit.Bukkit;
 import org.bukkit.OfflinePlayer;
 import org.bukkit.Server;
-import org.bukkit.World;
 import org.bukkit.craftbukkit.v1_21_R3.CraftServer;
-import org.bukkit.craftbukkit.v1_21_R3.CraftWorld;
 import org.bukkit.craftbukkit.v1_21_R3.entity.CraftPlayer;
 import org.bukkit.craftbukkit.v1_21_R3.event.CraftEventFactory;
 import org.bukkit.entity.Player;
@@ -33,22 +28,10 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.lang.reflect.Field;
-import java.util.UUID;
 import java.util.logging.Logger;
 
 public class PlayerManager implements com.lishid.openinv.internal.PlayerManager {
 
-  private static boolean paper;
-
-  static {
-    try {
-      Class.forName("io.papermc.paper.configuration.Configuration");
-      paper = true;
-    } catch (ClassNotFoundException ignored) {
-      paper = false;
-    }
-  }
-
   private final @NotNull Logger logger;
   private @Nullable Field bukkitEntity;
 
@@ -158,48 +141,9 @@ public class PlayerManager implements com.lishid.openinv.internal.PlayerManager
     // Game type settings are also loaded separately.
     player.loadGameTypes(loadedData);
 
-    if (paper) {
-      // Paper: world is not loaded by ServerPlayer#load(CompoundTag).
-      parseWorld(player, loadedData);
-    }
-
     return true;
   }
 
-  private 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));
-      return;
-    }
-    if (bukkitWorld == null) {
-      spawnInDefaultWorld(player);
-      return;
-    }
-    player.setServerLevel(((CraftWorld) bukkitWorld).getHandle());
-  }
-
-  private void spawnInDefaultWorld(ServerPlayer player) {
-    ServerLevel level = player.server.getLevel(Level.OVERWORLD);
-    if (level != null) {
-      player.spawnIn(level);
-    } else {
-      logger.warning("Tried to load player with invalid world when no fallback was available!");
-    }
-  }
-
   private void injectPlayer(ServerPlayer player) throws IllegalAccessException {
     if (bukkitEntity == null) {
       return;

plugin/build.gradle.kts

@@ -11,7 +11,9 @@ dependencies {
   implementation(project(":openinvapi"))
   implementation(project(":openinvcommon"))
   implementation(project(":openinvadaptercommon"))
-  implementation(project(":openinvadapterspigot", configuration = "shadow"))
+  implementation(project(":openinvadapterpaper1_21_3"))
+  implementation(project(":openinvadapterpaper1_21_1"))
+  implementation(project(":openinvadapterspigot", configuration = "reobf"))
   implementation(libs.planarwrappers)
 }
 
@@ -24,7 +26,6 @@ tasks.jar {
 }
 
 tasks.shadowJar {
-  dependsOn(":openinvadapterspigot:reobf")
   minimize {
     exclude(":openinv**")
   }

plugin/src/main/java/com/lishid/openinv/util/InternalAccessor.java

@@ -35,9 +35,9 @@ import java.util.logging.Logger;
 
 public class InternalAccessor {
 
-    private @Nullable Accessor internal;
+    private static final boolean PAPER;
 
-    public InternalAccessor(@NotNull Logger logger, @NotNull LanguageManager lang) {
+    static {
         boolean paper = false;
         try {
             Class.forName("io.papermc.paper.configuration.GlobalConfiguration");
@@ -45,19 +45,15 @@ public class InternalAccessor {
         } catch (ClassNotFoundException ignored) {
             // Expect remapped server.
         }
+        PAPER = paper;
+    }
 
+    private @Nullable Accessor internal;
+
+    public InternalAccessor(@NotNull Logger logger, @NotNull LanguageManager lang) {
         try {
-            Version maxSupported = Version.of(1, 21, 4);
-            // Placeholders currently mandate 1.21.4 minimum.
-            Version minSupported = Version.of(1, 21, 4);
-            if (!paper) {
-                if (BukkitVersions.MINECRAFT.equals(maxSupported)) {
-                    internal = new com.lishid.openinv.internal.reobf.InternalAccessor(logger, lang);
-                }
-            } else if (BukkitVersions.MINECRAFT.greaterThanOrEqual(minSupported)
-                    && BukkitVersions.MINECRAFT.lessThanOrEqual(maxSupported)) {
-                internal = new com.lishid.openinv.internal.common.InternalAccessor(logger, lang);
-            }
+            internal = getAccessor(logger, lang);
+
             if (internal != null) {
                 InventoryAccess.setProvider(internal::get);
             }
@@ -67,6 +63,38 @@ public class InternalAccessor {
         }
     }
 
+    private @Nullable Accessor getAccessor(@NotNull Logger logger, @NotNull LanguageManager lang) {
+        Version maxSupported = Version.of(1, 21, 4);
+        Version minSupported = Version.of(1, 21, 1);
+
+        // Ensure version is in supported range.
+        if (BukkitVersions.MINECRAFT.greaterThan(maxSupported) || BukkitVersions.MINECRAFT.lessThan(minSupported)) {
+            return null;
+        }
+
+        // Load Spigot accessor.
+        if (!PAPER) {
+            if (BukkitVersions.MINECRAFT.equals(maxSupported)) {
+                // Current Spigot, remapped internals are available.
+                return new com.lishid.openinv.internal.reobf.InternalAccessor(logger, lang);
+            } else {
+                // Older Spigot; unsupported.
+                return null;
+            }
+        }
+
+        // Paper or a Paper fork, can use Mojang-mapped internals.
+        if (BukkitVersions.MINECRAFT.equals(maxSupported)) { // 1.21.4
+            return new com.lishid.openinv.internal.common.InternalAccessor(logger, lang);
+        } else if (BukkitVersions.MINECRAFT.lessThan(Version.of(1, 21, 3))) {
+            // 1.21.1-1.21.2 placeholder format
+            return new com.lishid.openinv.internal.paper1_21_1.InternalAccessor(logger, lang);
+        }
+
+        // 1.21.3
+        return new com.lishid.openinv.internal.paper1_21_3.InternalAccessor(logger, lang);
+    }
+
     public String getReleasesLink() {
         if (BukkitVersions.MINECRAFT.lessThan(Version.of(1, 4, 4))) { // Good luck.
             return "https://dev.bukkit.org/projects/openinv/files?&sort=datecreated";
@@ -134,6 +162,9 @@ public class InternalAccessor {
         if (BukkitVersions.MINECRAFT.equals(Version.of(1, 20, 5))) { // 1.20.5
             return "Unsupported; upgrade to 1.20.6: https://github.com/Jikoo/OpenInv/releases/tag/5.1.2";
         }
+        if (PAPER && BukkitVersions.MINECRAFT.greaterThanOrEqual(Version.of(1, 21, 1))) { // Paper 1.21.1-1.21.3
+            return "https://github.com/Jikoo/OpenInv/releases";
+        }
         if (BukkitVersions.MINECRAFT.lessThanOrEqual(Version.of(1, 21))) { // 1.20.4, 1.20.6, 1.21
             return "https://github.com/Jikoo/OpenInv/releases/tag/5.1.2";
         }

scripts/tag_release.sh

@@ -23,15 +23,15 @@ fi
 version="$1"
 snapshot="${version%.*}.$((${version##*.} + 1))-SNAPSHOT"
 
-mvn versions:set -DnewVersion="$version"
+sed -i s/version=.*/version="$version"/ gradle.properties
 
-git add .
+git add gradle.properties
 git commit -S -m "Bump version to $version for release"
 git tag -s "$version" -m "Release $version"
 
-mvn clean package -am -P all
+./gradlew build
 
-mvn versions:set -DnewVersion="$snapshot"
+sed -i s/version=.*/version="$snapshot"/ gradle.properties
 
-git add .
+git add gradle.properties
 git commit -S -m "Bump version to $snapshot for development"

settings.gradle.kts

@@ -18,6 +18,8 @@ project(":openinvcommon").projectDir = file("common")
 
 val internals = listOf(
   "common",
+  "paper1_21_3",
+  "paper1_21_1",
   "spigot"
 )
 for (internal in internals) {