A plugin is required to build inventories.

Signed-off-by: Chris Sanders <zidane@spongepowered.org>

src/main/java/org/spongepowered/api/item/inventory/Inventory.java

@@ -37,6 +37,7 @@ import org.spongepowered.api.item.inventory.query.QueryType;
 import org.spongepowered.api.item.inventory.query.QueryTypes;
 import org.spongepowered.api.item.inventory.transaction.InventoryTransactionResult;
 import org.spongepowered.api.item.inventory.type.ViewableInventory;
+import org.spongepowered.plugin.PluginContainer;
 
 import java.util.List;
 import java.util.Optional;
@@ -511,6 +512,13 @@ public interface Inventory extends ValueContainer {
          */
         interface EndStep {
 
+            /**
+             * Sets the {@link PluginContainer plugin}.
+             * @param plugin The plugin
+             * @return this step
+             */
+            EndStep plugin(PluginContainer plugin);
+
             /**
              * Sets a unique identifier. Can be retrieved later using. {@link Inventory#get(Key)} with {@link Keys#UNIQUE_ID}
              *

src/main/java/org/spongepowered/api/item/inventory/type/ViewableInventory.java

@@ -35,6 +35,7 @@ import org.spongepowered.api.item.inventory.ItemStackSnapshot;
 import org.spongepowered.api.item.inventory.Slot;
 import org.spongepowered.api.item.inventory.menu.InventoryMenu;
 import org.spongepowered.math.vector.Vector2i;
+import org.spongepowered.plugin.PluginContainer;
 
 import java.util.List;
 import java.util.Set;
@@ -250,6 +251,13 @@ public interface ViewableInventory extends Inventory {
 
         interface EndStep extends Builder {
 
+            /**
+             * Sets the {@link PluginContainer plugin}.
+             * @param plugin The plugin
+             * @return this step
+             */
+            EndStep plugin(PluginContainer plugin);
+
             /**
              * Sets a unique identifier. Can be retrieved later using. {@link Inventory#get(Key)} with {@link Keys#UNIQUE_ID}
              *