General ItemMeta fixes

== AT ==
private-f net/minecraft/world/item/ItemStack components
public net/minecraft/world/food/FoodProperties DEFAULT_EAT_SECONDS
public org/bukkit/craftbukkit/block/CraftBlockStates getBlockState(Lorg/bukkit/World;Lnet/minecraft/core/BlockPos;Lnet/minecraft/world/level/block/state/BlockState;Lnet/minecraft/world/level/block/entity/BlockEntity;)Lorg/bukkit/craftbukkit/block/CraftBlockState;
public net/minecraft/world/level/block/entity/BlockEntity saveId(Lnet/minecraft/nbt/CompoundTag;)V

Co-authored-by: GhastCraftHD <julius.gruenberg@leghast.de>

paper-server/patches/sources/net/minecraft/world/item/ItemStack.java.patch

@@ -169,7 +169,7 @@
 +            DataComponentPatch oldData = this.components.asPatch();
 +            int oldCount = this.getCount();
 +            ServerLevel world = (ServerLevel) context.getLevel();
- 
++
 +            if (!(item instanceof BucketItem/* || item instanceof SolidBucketItem*/)) { // if not bucket // Paper - Fix cancelled powdered snow bucket placement
 +                world.captureBlockStates = true;
 +                // special case bonemeal
@@ -200,7 +200,7 @@
 +                    structureEvent = new StructureGrowEvent(location, treeType, isBonemeal, (Player) entityhuman.getBukkitEntity(), (List< BlockState>) (List<? extends BlockState>) blocks);
 +                    org.bukkit.Bukkit.getPluginManager().callEvent(structureEvent);
 +                }
-+
+ 
 +                BlockFertilizeEvent fertilizeEvent = new BlockFertilizeEvent(CraftBlock.at(world, blockposition), (Player) entityhuman.getBukkitEntity(), (List< BlockState>) (List<? extends BlockState>) blocks);
 +                fertilizeEvent.setCancelled(structureEvent != null && structureEvent.isCancelled());
 +                org.bukkit.Bukkit.getPluginManager().callEvent(fertilizeEvent);
@@ -521,25 +521,24 @@
          player.awardStat(Stats.ITEM_CRAFTED.get(this.getItem()), amount);
          this.getItem().onCraftedBy(this, world, player);
      }
-@@ -770,6 +1028,12 @@
+@@ -768,7 +1026,13 @@
-         return this.getItem().useOnRelease(this);
-     }
  
+     public boolean useOnRelease() {
+         return this.getItem().useOnRelease(this);
++    }
++
 +    // CraftBukkit start
 +    public void restorePatch(DataComponentPatch datacomponentpatch) {
 +        this.components.restorePatch(datacomponentpatch);
-+    }
+     }
 +    // CraftBukkit end
-+
+ 
      @Nullable
      public <T> T set(DataComponentType<? super T> type, @Nullable T value) {
-         return this.components.set(type, value);
+@@ -805,6 +1069,25 @@
-@@ -803,8 +1067,27 @@
-             this.components.restorePatch(datacomponentpatch1);
-         } else {
              this.getItem().verifyComponentsAfterLoad(this);
-+        }
+         }
-+    }
+     }
 +
 +    // Paper start - (this is just a good no conflict location)
 +    public org.bukkit.inventory.ItemStack asBukkitMirror() {
@@ -555,9 +554,9 @@
 +    public org.bukkit.inventory.ItemStack getBukkitStack() {
 +        if (bukkitStack == null || bukkitStack.handle != this) {
 +            bukkitStack = org.bukkit.craftbukkit.inventory.CraftItemStack.asCraftMirror(this);
-         }
++        }
 +        return bukkitStack;
-     }
++    }
 +    // Paper end
  
      public void applyComponents(DataComponentPatch changes) {
@@ -598,7 +597,7 @@
          double d0 = modifier.amount();
          boolean flag = false;
  
-@@ -1091,6 +1374,14 @@
+@@ -1091,6 +1374,19 @@
          EnchantmentHelper.forEachModifier(this, slot, attributeModifierConsumer);
      }
  
@@ -607,13 +606,18 @@
 +    public void setItem(Item item) {
 +        this.bukkitStack = null; // Paper
 +        this.item = item;
++        // Paper start - change base component prototype
++        final DataComponentPatch patch = this.getComponentsPatch();
++        this.components = new PatchedDataComponentMap(this.item.components());
++        this.applyComponents(patch);
++        // Paper end - change base component prototype
 +    }
 +    // CraftBukkit end
 +
      public Component getDisplayName() {
          MutableComponent ichatmutablecomponent = Component.empty().append(this.getHoverName());
  
-@@ -1153,7 +1444,7 @@
+@@ -1153,7 +1449,7 @@
      }
  
      public void consume(int amount, @Nullable LivingEntity entity) {

paper-server/patches/sources/net/minecraft/world/level/block/entity/BlockEntity.java.patch

@@ -57,7 +57,19 @@
          return nbttagcompound;
      }
  
-@@ -234,7 +259,12 @@
+@@ -121,6 +146,11 @@
+         CompoundTag nbttagcompound = new CompoundTag();
+ 
+         this.saveAdditional(nbttagcompound, registries);
++        // Paper start - store PDC here as well
++        if (this.persistentDataContainer != null && !this.persistentDataContainer.isEmpty()) {
++            nbttagcompound.put("PublicBukkitValues", this.persistentDataContainer.toTagCompound());
++        }
++        // Paper end
+         return nbttagcompound;
+     }
+ 
+@@ -234,7 +264,12 @@
      public void fillCrashReportCategory(CrashReportCategory crashReportSection) {
          crashReportSection.setDetail("Name", this::getNameForReporting);
          if (this.level != null) {
@@ -71,7 +83,7 @@
              CrashReportCategory.populateBlockDetails(crashReportSection, this.level, this.worldPosition, this.level.getBlockState(this.worldPosition));
          }
      }
-@@ -263,13 +293,19 @@
+@@ -263,13 +298,19 @@
      }
  
      public final void applyComponents(DataComponentMap defaultComponents, DataComponentPatch components) {
@@ -93,7 +105,7 @@
              @Nullable
              @Override
              public <T> T get(DataComponentType<T> type) {
-@@ -284,9 +320,13 @@
+@@ -284,9 +325,13 @@
              }
          });
          Objects.requireNonNull(set);
@@ -108,7 +120,7 @@
      }
  
      protected void collectImplicitComponents(DataComponentMap.Builder builder) {}
-@@ -321,6 +361,30 @@
+@@ -321,6 +366,30 @@
          }
      }
  

paper-server/src/main/java/org/bukkit/craftbukkit/block/CraftBlockEntityState.java

@@ -151,6 +151,19 @@ public abstract class CraftBlockEntityState<T extends BlockEntity> extends Craft
         return this.snapshot.getUpdateTag(this.getRegistryAccess());
     }
 
+    // Paper start - properly save blockentity itemstacks
+    public CompoundTag getSnapshotCustomNbtOnly() {
+        this.applyTo(this.snapshot);
+        final CompoundTag nbt = this.snapshot.saveCustomOnly(this.getRegistryAccess());
+        this.snapshot.removeComponentsFromTag(nbt);
+        if (!nbt.isEmpty()) {
+            // have to include the "id" if it's going to have block entity data
+            this.snapshot.saveId(nbt);
+        }
+        return nbt;
+    }
+    // Paper end
+
     // copies the data of the given tile entity to this block state
     protected void load(T tileEntity) {
         if (tileEntity != null && tileEntity != this.snapshot) {

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java

@@ -291,7 +291,9 @@ public final class CraftItemStack extends ItemStack {
 
     @Override
     public void removeEnchantments() {
-        this.handle.remove(DataComponents.ENCHANTMENTS);
+        if (this.handle != null) { // Paper - fix NPE
+        this.handle.set(DataComponents.ENCHANTMENTS, ItemEnchantments.EMPTY); // Paper - set to default instead of removing the component
+        } // Paper
     }
 
     @Override
@@ -353,7 +355,14 @@ public final class CraftItemStack extends ItemStack {
     // Paper end - improve handled tags on type change
     // Paper start
     public static void applyMetaToItem(net.minecraft.world.item.ItemStack itemStack, ItemMeta itemMeta) {
-        final CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator();
+        // Paper start - support updating profile after resolving it
+        final CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator() {
+            @Override
+            void skullCallback(final net.minecraft.world.item.component.ResolvableProfile profile) {
+                itemStack.set(DataComponents.PROFILE, profile);
+            }
+        };
+        // Paper end - support updating profile after resolving it
         ((CraftMetaItem) itemMeta).applyToItem(tag);
         itemStack.applyComponents(tag.build());
     }
@@ -401,15 +410,20 @@ public final class CraftItemStack extends ItemStack {
         if (itemMeta == null) return true;
 
         if (!((CraftMetaItem) itemMeta).isEmpty()) {
-            CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator();
+            // Paper start - support updating profile after resolving it
+            CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator() {
+                @Override
+                void skullCallback(final net.minecraft.world.item.component.ResolvableProfile resolvableProfile) {
+                    item.set(DataComponents.PROFILE, resolvableProfile);
+                }
+            };
+            // Paper end - support updating profile after resolving it
 
             ((CraftMetaItem) itemMeta).applyToItem(tag);
-            item.restorePatch(tag.build());
+            item.restorePatch(DataComponentPatch.EMPTY); // Paper - properly apply the new patch from itemmeta
-        }
+            item.applyComponents(tag.build()); // Paper - properly apply the new patch from itemmeta
-        // SpigotCraft#463 this is required now by the Vanilla client, so mimic ItemStack constructor in ensuring it
-        if (item.getItem() != null && item.getMaxDamage() > 0) {
-            item.setDamageValue(item.getDamageValue());
         }
+        // Paper - this is no longer needed
 
         return true;
     }

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaAxolotlBucket.java

@@ -118,14 +118,13 @@ public class CraftMetaAxolotlBucket extends CraftMetaItem implements AxolotlBuck
 
     @Override
     public Axolotl.Variant getVariant() {
+        com.google.common.base.Preconditions.checkState(this.hasVariant(), "Variant is absent, check hasVariant first!"); // Paper - fix NPE
         return Axolotl.Variant.values()[this.variant];
     }
 
     @Override
     public void setVariant(Axolotl.Variant variant) {
-        if (variant == null) {
+        com.google.common.base.Preconditions.checkArgument(variant != null, "Variant cannot be null!"); // Paper
-            variant = Axolotl.Variant.LUCY;
-        }
         this.variant = variant.ordinal();
     }
 

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBanner.java

@@ -69,6 +69,7 @@ public class CraftMetaBanner extends CraftMetaItem implements BannerMeta {
     void applyToItem(CraftMetaItem.Applicator tag) {
         super.applyToItem(tag);
 
+        if (this.patterns.isEmpty()) return; // Paper - don't write empty patterns
         List<BannerPatternLayers.Layer> newPatterns = new ArrayList<>();
 
         for (Pattern p : this.patterns) {

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBlockState.java

@@ -52,10 +52,24 @@ public class CraftMetaBlockState extends CraftMetaItem implements BlockStateMeta
 
     @ItemMetaKey.Specific(ItemMetaKey.Specific.To.NBT)
     static final ItemMetaKeyType<CustomData> BLOCK_ENTITY_TAG = new ItemMetaKeyType<>(DataComponents.BLOCK_ENTITY_DATA, "BlockEntityTag");
+    static final ItemMetaKey BLOCK_ENTITY_TAG_CUSTOM_DATA = new ItemMetaKey("block-entity-tag"); // Paper
+    static final ItemMetaKey BLOCK_ENTITY_COMPONENTS = new ItemMetaKey("block-entity-components"); // Paper
 
     final Material material;
-    private CraftBlockEntityState<?> blockEntityTag;
+    // Paper start - store data separately
-    private BlockVector position;
+    DataComponentMap components;
+    CustomData blockEntityTag;
+    {
+        // this is because the fields are possibly assigned in the super constructor (via deserializeInternal)
+        // and a direct field initialization happens **after** the super constructor. So we only want to
+        // set them to empty if they weren't assigned by the super constructor (via deserializeInternal)
+        this.components = this.components != null ? this.components : DataComponentMap.EMPTY;
+        this.blockEntityTag = this.blockEntityTag != null ? this.blockEntityTag : CustomData.EMPTY;
+    }
+    private Material materialForBlockEntityType() {
+        return this.material;
+    }
+    // Paper end
     private CompoundTag internalTag;
 
     CraftMetaBlockState(CraftMetaItem meta, Material material) {
@@ -64,47 +78,61 @@ public class CraftMetaBlockState extends CraftMetaItem implements BlockStateMeta
 
         if (!(meta instanceof CraftMetaBlockState)
                 || ((CraftMetaBlockState) meta).material != material) {
-            this.blockEntityTag = null;
+            // Paper start
+            this.components = DataComponentMap.EMPTY;
+            this.blockEntityTag = CustomData.EMPTY;
+            // Paper end
             return;
         }
 
         CraftMetaBlockState te = (CraftMetaBlockState) meta;
+        // Paper start
+        this.components = te.components;
         this.blockEntityTag = te.blockEntityTag;
-        this.position = te.position;
+        // Paper end
     }
 
     CraftMetaBlockState(DataComponentPatch tag, Material material, final Set<DataComponentType<?>> extraHandledDcts) { // Paper
         super(tag, extraHandledDcts); // Paper
         this.material = material;
 
-        getOrEmpty(tag, CraftMetaBlockState.BLOCK_ENTITY_TAG).ifPresent((blockTag) -> {
+        // Paper start - move to separate method to be re-called
-            CompoundTag nbt = blockTag.copyTag();
+        this.updateBlockState(tag);
-
-            this.blockEntityTag = CraftMetaBlockState.getBlockState(material, nbt);
-            if (nbt.contains("x", CraftMagicNumbers.NBT.TAG_ANY_NUMBER) && nbt.contains("y", CraftMagicNumbers.NBT.TAG_ANY_NUMBER) && nbt.contains("z", CraftMagicNumbers.NBT.TAG_ANY_NUMBER)) {
-                this.position = new BlockVector(nbt.getInt("x"), nbt.getInt("y"), nbt.getInt("z"));
     }
+
+    private void updateBlockState(final DataComponentPatch tag) {
+        // Paper end
+        getOrEmpty(tag, CraftMetaBlockState.BLOCK_ENTITY_TAG).ifPresent((nbt) -> {
+            this.blockEntityTag = nbt; // Paper
         });
 
         if (!tag.isEmpty()) {
-            CraftBlockEntityState<?> blockEntityTag = this.blockEntityTag;
+            // Paper start - store data in a DataComponentMap to be used to construct CraftBlockEntityStates
-            if (blockEntityTag == null) {
+            final DataComponentMap.Builder map = DataComponentMap.builder();
-                blockEntityTag = CraftMetaBlockState.getBlockState(material, null);
+            final net.minecraft.world.level.block.entity.BlockEntity dummyBlockEntity = java.util.Objects.requireNonNull(
-            }
+                org.bukkit.craftbukkit.block.CraftBlockStates.createNewTileEntity(this.materialForBlockEntityType())
+            );
 
-            // Convert to map
+            // we don't care about what's in here, all
-            PatchedDataComponentMap map = new PatchedDataComponentMap(DataComponentMap.EMPTY);
+            // we want is to know which data component types are referenced
-            map.applyPatch(tag);
+            Set<DataComponentType<?>> applied = dummyBlockEntity.applyComponentsSet(DataComponentMap.EMPTY, DataComponentPatch.EMPTY);
-            // Apply
+            // Paper end - store data in a DataComponentMap to be used to construct CraftBlockEntityStates
-            Set<DataComponentType<?>> applied = blockEntityTag.applyComponents(map, tag);
             // Mark applied components as handled
             for (DataComponentType<?> seen : applied) {
                 this.unhandledTags.clear(seen);
             }
             // Only set blockEntityTag if something was applied
             if (!applied.isEmpty()) {
-                this.blockEntityTag = blockEntityTag;
+                // Paper start
+                for (final DataComponentType type : applied) {
+                    if (CraftMetaItem.DEFAULT_HANDLED_DCTS.contains(type)) continue;
+                    getOrEmpty(tag, type).ifPresent(value -> {
+                        map.set(type, value);
+                    });
                 }
+                // Paper end
+            }
+            this.components = map.build(); // Paper
         }
     }
 
@@ -118,42 +146,43 @@ public class CraftMetaBlockState extends CraftMetaItem implements BlockStateMeta
             this.material = Material.AIR;
         }
         if (this.internalTag != null) {
-            this.blockEntityTag = CraftMetaBlockState.getBlockState(this.material, this.internalTag);
+            this.setBlockState(CraftMetaBlockState.getBlockState(this.material, this.internalTag)); // Paper - general item meta fixes - pass through setter
             this.internalTag = null;
         }
-        this.position = SerializableMeta.getObject(BlockVector.class, map, "blockPosition", true);
+        // Paper start - general item meta fixes - parse spigot legacy position and merge into block entity tag
+        final BlockVector legacyPosition = SerializableMeta.getObject(BlockVector.class, map, "blockPosition", true);
+        if (legacyPosition != null) {
+            this.blockEntityTag = this.blockEntityTag.update(t -> {
+                if (t.isEmpty()) {
+                    BlockEntity.addEntityType(t, java.util.Objects.requireNonNull(CraftBlockStates.getBlockEntityType(this.materialForBlockEntityType())));
+                }
+                t.putInt("x", legacyPosition.getBlockX());
+                t.putInt("y", legacyPosition.getBlockY());
+                t.putInt("z", legacyPosition.getBlockZ());
+            });
+        }
+        // Paper end - general item meta fixes - parse spigot legacy position and merge into block entity tag
     }
 
     @Override
     void applyToItem(CraftMetaItem.Applicator tag) {
         super.applyToItem(tag);
 
-        CompoundTag nbt = null;
+        // Paper start - accurately replicate logic for creating ItemStack from BlockEntity
-        if (this.blockEntityTag != null) {
+        // taken from BlockEntity#saveToItem and BlockItem#setBlockEntityData
-            nbt = this.blockEntityTag.getItemNBT();
+        final CompoundTag nbt = this.blockEntityTag.copyTag();
-
+        if (nbt.contains("id", CraftMagicNumbers.NBT.TAG_STRING)) {
-            for (TypedDataComponent<?> component : this.blockEntityTag.collectComponents()) {
+            tag.put(CraftMetaBlockState.BLOCK_ENTITY_TAG, CustomData.of(nbt));
-                tag.putIfAbsent(component);
+        } else if (!nbt.isEmpty()) {
-            }
+            BlockEntity.addEntityType(nbt, java.util.Objects.requireNonNull(CraftBlockStates.getBlockEntityType(this.materialForBlockEntityType())));
-        }
-
-        if (this.position != null) {
-            if (nbt == null) {
-                nbt = new CompoundTag();
-            }
-
-            nbt.putInt("x", this.position.getBlockX());
-            nbt.putInt("y", this.position.getBlockY());
-            nbt.putInt("z", this.position.getBlockZ());
-        }
-
-        if (nbt != null && !nbt.isEmpty()) {
-            CraftBlockEntityState<?> tile = (this.blockEntityTag != null) ? this.blockEntityTag : CraftMetaBlockState.getBlockState(this.material, null);
-            // See ItemBlock#setBlockEntityData
-            tile.addEntityType(nbt);
-
             tag.put(CraftMetaBlockState.BLOCK_ENTITY_TAG, CustomData.of(nbt));
         }
+
+        for (final TypedDataComponent<?> component : this.components) {
+            if (CraftMetaItem.DEFAULT_HANDLED_DCTS.contains(component.type())) continue; // if the component type was already handled by CraftMetaItem, don't add it again
+            tag.builder.set(component);
+        }
+        // Paper end
     }
 
     @Override
@@ -162,23 +191,35 @@ public class CraftMetaBlockState extends CraftMetaItem implements BlockStateMeta
 
         if (tag.contains(CraftMetaBlockState.BLOCK_ENTITY_TAG.NBT, CraftMagicNumbers.NBT.TAG_COMPOUND)) {
             this.internalTag = tag.getCompound(CraftMetaBlockState.BLOCK_ENTITY_TAG.NBT);
+            return; // Paper - if legacy, don't check anything else
         }
+        // Paper start - new serialization format
+        if (tag.contains(CraftMetaBlockState.BLOCK_ENTITY_TAG_CUSTOM_DATA.NBT, CraftMagicNumbers.NBT.TAG_COMPOUND)) {
+            this.blockEntityTag = CustomData.of(tag.getCompound(CraftMetaBlockState.BLOCK_ENTITY_TAG_CUSTOM_DATA.NBT));
+        }
+        if (tag.contains(CraftMetaBlockState.BLOCK_ENTITY_COMPONENTS.NBT, CraftMagicNumbers.NBT.TAG_COMPOUND)) {
+            this.components = DataComponentMap.CODEC.parse(org.bukkit.craftbukkit.CraftRegistry.getMinecraftRegistry().createSerializationContext(net.minecraft.nbt.NbtOps.INSTANCE), tag.getCompound(CraftMetaBlockState.BLOCK_ENTITY_COMPONENTS.NBT)).getOrThrow();
+        }
+        // Paper end - new serialization format
     }
 
     @Override
     void serializeInternal(final Map<String, Tag> internalTags) {
-        if (this.blockEntityTag != null) {
+        // Paper start - new serialization format
-            internalTags.put(CraftMetaBlockState.BLOCK_ENTITY_TAG.NBT, this.blockEntityTag.getSnapshotNBT());
+        if (!this.blockEntityTag.isEmpty()) {
+            internalTags.put(CraftMetaBlockState.BLOCK_ENTITY_TAG_CUSTOM_DATA.NBT, this.blockEntityTag.getUnsafe()); // unsafe because it's serialized right away
         }
+        if (!this.components.isEmpty()) {
+            final Tag componentsTag = DataComponentMap.CODEC.encodeStart(org.bukkit.craftbukkit.CraftRegistry.getMinecraftRegistry().createSerializationContext(net.minecraft.nbt.NbtOps.INSTANCE), this.components).getOrThrow();
+            internalTags.put(CraftMetaBlockState.BLOCK_ENTITY_COMPONENTS.NBT, componentsTag);
+        }
+        // Paper end - new serialization format
     }
 
     @Override
     ImmutableMap.Builder<String, Object> serialize(ImmutableMap.Builder<String, Object> builder) {
         super.serialize(builder);
         builder.put("blockMaterial", this.material.name());
-        if (this.position != null) {
-            builder.put("blockPosition", this.position);
-        }
         return builder;
     }
 
@@ -186,12 +227,10 @@ public class CraftMetaBlockState extends CraftMetaItem implements BlockStateMeta
     int applyHash() {
         final int original;
         int hash = original = super.applyHash();
-        if (this.blockEntityTag != null) {
+        // Paper start
         hash = 61 * hash + this.blockEntityTag.hashCode();
-        }
+        hash = 61 * hash + this.components.hashCode();
-        if (this.position != null) {
+        // Paper end
-            hash = 61 * hash + this.position.hashCode();
-        }
         return original != hash ? CraftMetaBlockState.class.hashCode() ^ hash : hash;
     }
 
@@ -203,52 +242,75 @@ public class CraftMetaBlockState extends CraftMetaItem implements BlockStateMeta
         if (meta instanceof CraftMetaBlockState) {
             CraftMetaBlockState that = (CraftMetaBlockState) meta;
 
-            return Objects.equal(this.blockEntityTag, that.blockEntityTag) && Objects.equal(this.position, that.position);
+            return Objects.equal(this.blockEntityTag, that.blockEntityTag) && Objects.equal(this.components, that.components); // Paper
         }
         return true;
     }
 
     boolean isBlockStateEmpty() {
-        return !(this.blockEntityTag != null || this.position != null);
+        return !(this.blockEntityTag != null);
     }
 
     @Override
     boolean notUncommon(CraftMetaItem meta) {
-        return super.notUncommon(meta) && (meta instanceof CraftMetaBlockState || this.isBlockStateEmpty());
+        return super.notUncommon(meta) && (meta instanceof CraftMetaBlockState || (this.blockEntityTag.isEmpty() && this.components.isEmpty())); // Paper
     }
 
     @Override
     boolean isEmpty() {
-        return super.isEmpty() && this.isBlockStateEmpty();
+        return super.isEmpty() && this.blockEntityTag.isEmpty() && this.components.isEmpty(); // Paper
     }
 
     @Override
     public CraftMetaBlockState clone() {
         CraftMetaBlockState meta = (CraftMetaBlockState) super.clone();
-        if (this.blockEntityTag != null) {
+        // Paper start - no need for "clone" because they are essentially immutables
-            meta.blockEntityTag = this.blockEntityTag.copy();
+        meta.blockEntityTag = this.blockEntityTag;
-        }
+        meta.components = this.components;
-        if (this.position != null) {
+        // Paper end
-            meta.position = this.position.clone();
-        }
         return meta;
     }
 
     @Override
     public boolean hasBlockState() {
-        return this.blockEntityTag != null;
+        return !this.blockEntityTag.isEmpty() || !this.components.isEmpty(); // Paper
     }
 
     // Paper start - add method to clear block state
     @Override
     public void clearBlockState() {
-        this.blockEntityTag = null;
+        // Paper start
+        this.blockEntityTag = CustomData.EMPTY;
+        this.components = DataComponentMap.EMPTY;
+        // Paper end
     }
     // Paper end - add method to clear block state
 
     @Override
-    public BlockState getBlockState() {
+    // Paper start - create blockstate on-demand
-        return (this.blockEntityTag != null) ? this.blockEntityTag.copy() : CraftMetaBlockState.getBlockState(this.material, null);
+    public CraftBlockEntityState<?> getBlockState() {
+        BlockPos pos = BlockPos.ZERO;
+        final Material stateMaterial = this.materialForBlockEntityType();
+        if (!this.blockEntityTag.isEmpty()) {
+            // Paper "id" field is always present now
+            pos = BlockEntity.getPosFromTag(this.blockEntityTag.getUnsafe()); // unsafe is fine here, just querying
+        }
+        final net.minecraft.world.level.block.entity.BlockEntityType<?> type = java.util.Objects.requireNonNull(CraftBlockStates.getBlockEntityType(stateMaterial));
+        final net.minecraft.world.level.block.state.BlockState nmsBlockState = ((org.bukkit.craftbukkit.block.data.CraftBlockData) this.getBlockData(stateMaterial)).getState();
+        final net.minecraft.world.level.block.entity.BlockEntity blockEntity = java.util.Objects.requireNonNull(type.create(pos, nmsBlockState));
+        if (!this.blockEntityTag.isEmpty()) {
+            this.blockEntityTag.loadInto(blockEntity, org.bukkit.craftbukkit.CraftRegistry.getMinecraftRegistry());
+        }
+        final PatchedDataComponentMap patchedMap = new PatchedDataComponentMap(nmsBlockState.getBlock().asItem().components());
+        patchedMap.setAll(this.components);
+        final Applicator applicator = new Applicator() {};
+        super.applyToItem(applicator);
+        patchedMap.applyPatch(applicator.build());
+        blockEntity.applyComponents(nmsBlockState.getBlock().asItem().components(), patchedMap.asPatch());
+
+        // This is expected to always return a CraftBlockEntityState for the passed material:
+        return (CraftBlockEntityState<?>) CraftBlockStates.getBlockState(null, pos, nmsBlockState, blockEntity);
+        // Paper end
     }
 
     private static CraftBlockEntityState<?> getBlockState(Material material, CompoundTag blockEntityTag) {
@@ -278,7 +340,23 @@ public class CraftMetaBlockState extends CraftMetaItem implements BlockStateMeta
         Class<?> blockStateType = CraftBlockStates.getBlockStateType(stateMaterial);
         Preconditions.checkArgument(blockStateType == blockState.getClass() && blockState instanceof CraftBlockEntityState, "Invalid blockState for %s", this.material);
 
-        this.blockEntityTag = (CraftBlockEntityState<?>) blockState;
+        // Paper start - when a new BlockState is set, the components from that block entity
+        // have to be used to update the fields on CraftMetaItem
+        final CraftBlockEntityState<?> craftBlockState = (CraftBlockEntityState<?>) blockState;
+        final CompoundTag data = craftBlockState.getSnapshotCustomNbtOnly();
+        final PatchedDataComponentMap patchedMap = new net.minecraft.core.component.PatchedDataComponentMap(craftBlockState.getHandle().getBlock().asItem().components());
+        final net.minecraft.core.component.DataComponentMap map = craftBlockState.collectComponents();
+        patchedMap.setAll(map);
+        if (!data.isEmpty()) {
+            patchedMap.set(BLOCK_ENTITY_TAG.TYPE, CustomData.of(data));
+        }
+        final DataComponentPatch patch = patchedMap.asPatch();
+        this.updateFromPatch(patch, null);
+        // we have to reset the fields because this should be like a "new" block entity is being used
+        this.blockEntityTag = CustomData.EMPTY;
+        this.components = DataComponentMap.EMPTY;
+        this.updateBlockState(patch);
+        // Paper end
     }
 
     private static Material shieldToBannerHack(CompoundTag tag) {

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBook.java

@@ -34,7 +34,7 @@ public class CraftMetaBook extends CraftMetaItem implements BookMeta, WritableBo
     @ItemMetaKey.Specific(ItemMetaKey.Specific.To.NBT)
     static final ItemMetaKeyType<WritableBookContent> BOOK_CONTENT = new ItemMetaKeyType<>(DataComponents.WRITABLE_BOOK_CONTENT);
     static final ItemMetaKey BOOK_PAGES = new ItemMetaKey("pages");
-    static final int MAX_PAGES = Integer.MAX_VALUE; // SPIGOT-6911: Use Minecraft limits
+    static final int MAX_PAGES = WritableBookContent.MAX_PAGES; // SPIGOT-6911: Use Minecraft limits // Paper
     static final int MAX_PAGE_LENGTH = WritableBookContent.PAGE_EDIT_LENGTH; // SPIGOT-6911: Use Minecraft limits
 
     // We store the pages in their raw original text representation. See SPIGOT-5063, SPIGOT-5350, SPIGOT-3206

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBookSigned.java

@@ -124,13 +124,13 @@ public class CraftMetaBookSigned extends CraftMetaItem implements BookMeta {
     void applyToItem(CraftMetaItem.Applicator itemData) {
         super.applyToItem(itemData);
 
+        List<Filterable<Component>> list = new ArrayList<>(); // Paper - General ItemMeta Fixes
         if (this.pages != null) {
-            List<Filterable<Component>> list = new ArrayList<>();
             for (Component page : this.pages) {
                 list.add(Filterable.passThrough(page));
             }
-            itemData.put(CraftMetaBookSigned.BOOK_CONTENT, new WrittenBookContent(Filterable.from(FilteredText.passThrough(this.title)), this.author, this.generation, list, this.resolved));
         }
+        itemData.put(CraftMetaBookSigned.BOOK_CONTENT, new WrittenBookContent(Filterable.from(this.title == null ? FilteredText.EMPTY : FilteredText.passThrough(this.title)), this.author == null ? "" : this.author, this.generation, list, this.resolved)); // Paper - General ItemMeta Fixes
     }
 
     @Override

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBundle.java

@@ -41,7 +41,7 @@ public class CraftMetaBundle extends CraftMetaItem implements BundleMeta {
             bundle.items().forEach((item) -> {
                 ItemStack itemStack = CraftItemStack.asCraftMirror(item);
 
-                if (!itemStack.getType().isAir()) { // SPIGOT-7174 - Avoid adding air
+                if (!itemStack.isEmpty()) { // SPIGOT-7174 - Avoid adding air // Paper
                     this.addItem(itemStack);
                 }
             });
@@ -54,7 +54,7 @@ public class CraftMetaBundle extends CraftMetaItem implements BundleMeta {
         Iterable<?> items = SerializableMeta.getObject(Iterable.class, map, CraftMetaBundle.ITEMS.BUKKIT, true);
         if (items != null) {
             for (Object stack : items) {
-                if (stack instanceof ItemStack itemStack && !itemStack.getType().isAir()) { // SPIGOT-7174 - Avoid adding air
+                if (stack instanceof ItemStack itemStack && !itemStack.isEmpty()) { // SPIGOT-7174 - Avoid adding air // Paper
                     this.addItem(itemStack);
                 }
             }
@@ -110,7 +110,7 @@ public class CraftMetaBundle extends CraftMetaItem implements BundleMeta {
 
     @Override
     public void addItem(ItemStack item) {
-        Preconditions.checkArgument(item != null && !item.getType().isAir(), "item is null or air");
+        Preconditions.checkArgument(item != null && !item.isEmpty(), "item is null or empty"); // Paper
 
         if (this.items == null) {
             this.items = new ArrayList<>();

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaColorableArmor.java

@@ -11,16 +11,30 @@ import org.bukkit.inventory.meta.ColorableArmorMeta;
 @DelegateDeserialization(SerializableMeta.class)
 public class CraftMetaColorableArmor extends CraftMetaArmor implements ColorableArmorMeta {
 
-    private Color color = DEFAULT_LEATHER_COLOR;
+    private Integer color; // Paper - keep color component consistent with vanilla (top byte is ignored)
 
     CraftMetaColorableArmor(CraftMetaItem meta) {
         super(meta);
-        CraftMetaLeatherArmor.readColor(this, meta);
+        // Paper start
+        if (!(meta instanceof CraftMetaColorableArmor armorMeta)) {
+            return;
+        }
+
+        this.color = armorMeta.color;
+        // Paper end
     }
 
     CraftMetaColorableArmor(DataComponentPatch tag, java.util.Set<net.minecraft.core.component.DataComponentType<?>> extraHandledDcts) { // Paper
         super(tag, extraHandledDcts); // Paper
-        CraftMetaLeatherArmor.readColor(this, tag);
+        // Paper start
+        getOrEmpty(tag, CraftMetaLeatherArmor.COLOR).ifPresent((dyedItemColor) -> {
+            if (!dyedItemColor.showInTooltip()) {
+                this.addItemFlags(org.bukkit.inventory.ItemFlag.HIDE_DYE);
+            }
+
+            this.color = dyedItemColor.rgb();
+        });
+        // Paper end
     }
 
     CraftMetaColorableArmor(Map<String, Object> map) {
@@ -31,7 +45,11 @@ public class CraftMetaColorableArmor extends CraftMetaArmor implements Colorable
     @Override
     void applyToItem(CraftMetaItem.Applicator itemTag) {
         super.applyToItem(itemTag);
-        CraftMetaLeatherArmor.applyColor(this, itemTag);
+        // Paper start
+        if (this.hasColor()) {
+            itemTag.put(CraftMetaLeatherArmor.COLOR, new net.minecraft.world.item.component.DyedItemColor(this.color, !this.hasItemFlag(org.bukkit.inventory.ItemFlag.HIDE_DYE)));
+        }
+        // Paper end
     }
 
     @Override
@@ -52,16 +70,16 @@ public class CraftMetaColorableArmor extends CraftMetaArmor implements Colorable
 
     @Override
     public Color getColor() {
-        return this.color;
+        return this.color == null ? DEFAULT_LEATHER_COLOR : Color.fromRGB(this.color & 0xFFFFFF); // Paper - this should really be nullable
     }
 
     @Override
     public void setColor(Color color) {
-        this.color = color == null ? DEFAULT_LEATHER_COLOR : color;
+        this.color = color == null ? null : color.asRGB(); // Paper
     }
 
     boolean hasColor() {
-        return CraftMetaLeatherArmor.hasColor(this);
+        return this.color != null; // Paper
     }
 
     @Override
@@ -81,7 +99,7 @@ public class CraftMetaColorableArmor extends CraftMetaArmor implements Colorable
         if (meta instanceof CraftMetaColorableArmor) {
             CraftMetaColorableArmor that = (CraftMetaColorableArmor) meta;
 
-            return this.color.equals(that.color);
+            return this.hasColor() ? that.hasColor() && this.color.equals(that.color) : !that.hasColor(); // Paper - allow null
         }
         return true;
     }

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaCompass.java

@@ -31,11 +31,7 @@ public class CraftMetaCompass extends CraftMetaItem implements CompassMeta {
     static final ItemMetaKey LODESTONE_POS_Z = new ItemMetaKey("LodestonePosZ");
     static final ItemMetaKey LODESTONE_TRACKED = new ItemMetaKey("LodestoneTracked");
 
-    private ResourceKey<net.minecraft.world.level.Level> lodestoneWorld;
+    private LodestoneTracker tracker; // Paper - use LodestoneTracker type
-    private int lodestoneX;
-    private int lodestoneY;
-    private int lodestoneZ;
-    private boolean tracked = true;
 
     CraftMetaCompass(CraftMetaItem meta) {
         super(meta);
@@ -43,24 +39,13 @@ public class CraftMetaCompass extends CraftMetaItem implements CompassMeta {
             return;
         }
         CraftMetaCompass compassMeta = (CraftMetaCompass) meta;
-        this.lodestoneWorld = compassMeta.lodestoneWorld;
+        this.tracker = compassMeta.tracker; // Paper - use LodestoneTracker type
-        this.lodestoneX = compassMeta.lodestoneX;
-        this.lodestoneY = compassMeta.lodestoneY;
-        this.lodestoneZ = compassMeta.lodestoneZ;
-        this.tracked = compassMeta.tracked;
     }
 
     CraftMetaCompass(DataComponentPatch tag, java.util.Set<net.minecraft.core.component.DataComponentType<?>> extraHandledDcts) { // Paper
         super(tag, extraHandledDcts); // Paper
         getOrEmpty(tag, CraftMetaCompass.LODESTONE_TARGET).ifPresent((lodestoneTarget) -> {
-            lodestoneTarget.target().ifPresent((target) -> {
+            this.tracker = lodestoneTarget; // Paper - use LodestoneTracker type
-                this.lodestoneWorld = target.dimension();
-                BlockPos pos = target.pos();
-                this.lodestoneX = pos.getX();
-                this.lodestoneY = pos.getY();
-                this.lodestoneZ = pos.getZ();
-            });
-            this.tracked = lodestoneTarget.tracked();
         });
     }
 
@@ -68,10 +53,13 @@ public class CraftMetaCompass extends CraftMetaItem implements CompassMeta {
         super(map);
         String lodestoneWorldString = SerializableMeta.getString(map, CraftMetaCompass.LODESTONE_POS_WORLD.BUKKIT, true);
         if (lodestoneWorldString != null) {
-            this.lodestoneWorld = ResourceKey.create(Registries.DIMENSION, ResourceLocation.tryParse(lodestoneWorldString));
+            // Paper start - use LodestoneTracker type
-            this.lodestoneX = (Integer) map.get(CraftMetaCompass.LODESTONE_POS_X.BUKKIT);
+            ResourceKey<net.minecraft.world.level.Level> lodestoneWorld = ResourceKey.create(Registries.DIMENSION, ResourceLocation.tryParse(lodestoneWorldString));
-            this.lodestoneY = (Integer) map.get(CraftMetaCompass.LODESTONE_POS_Y.BUKKIT);
+            int lodestoneX = (Integer) map.get(CraftMetaCompass.LODESTONE_POS_X.BUKKIT);
-            this.lodestoneZ = (Integer) map.get(CraftMetaCompass.LODESTONE_POS_Z.BUKKIT);
+            int lodestoneY = (Integer) map.get(CraftMetaCompass.LODESTONE_POS_Y.BUKKIT);
+            int lodestoneZ = (Integer) map.get(CraftMetaCompass.LODESTONE_POS_Z.BUKKIT);
+            this.tracker = new LodestoneTracker(Optional.of(new GlobalPos(lodestoneWorld, new BlockPos(lodestoneX, lodestoneY, lodestoneZ))), true);
+            // Paper end - use LodestoneTracker type
         } else {
             // legacy
             Location lodestone = SerializableMeta.getObject(Location.class, map, CraftMetaCompass.LODESTONE_POS.BUKKIT, true);
@@ -79,21 +67,22 @@ public class CraftMetaCompass extends CraftMetaItem implements CompassMeta {
                 this.setLodestone(lodestone);
             }
         }
-        this.tracked = SerializableMeta.getBoolean(map, CraftMetaCompass.LODESTONE_TRACKED.BUKKIT);
+        // Paper start - use LodestoneTracker type
+        final Optional<Boolean> tracked = SerializableMeta.getObjectOptionally(Boolean.class, map, CraftMetaCompass.LODESTONE_TRACKED.BUKKIT, true);
+        final Optional<GlobalPos> trackedPos = this.tracker != null ? this.tracker.target() : Optional.empty();
+        tracked.ifPresent(isTracked -> this.tracker = new LodestoneTracker(trackedPos, isTracked));
+        // Paper end - use LodestoneTracker type
     }
 
     @Override
     void applyToItem(CraftMetaItem.Applicator tag) {
         super.applyToItem(tag);
 
-        Optional<GlobalPos> target = Optional.empty();
+        // Paper start - use LodestoneTracker type
-        if (this.lodestoneWorld != null) {
+        if (this.tracker != null) {
-            target = Optional.of(new GlobalPos(this.lodestoneWorld, new BlockPos(this.lodestoneX, this.lodestoneY, this.lodestoneZ)));
+            tag.put(CraftMetaCompass.LODESTONE_TARGET, this.tracker);
-        }
-
-        if (target.isPresent() || this.hasLodestoneTracked()) {
-            tag.put(CraftMetaCompass.LODESTONE_TARGET, new LodestoneTracker(target, this.tracked));
         }
+        // Paper end - use LodestoneTracker type
     }
 
     @Override
@@ -102,7 +91,7 @@ public class CraftMetaCompass extends CraftMetaItem implements CompassMeta {
     }
 
     boolean isCompassEmpty() {
-        return !(this.hasLodestone() || this.hasLodestoneTracked());
+        return this.tracker == null; // Paper - use LodestoneTracker type
     }
 
     @Override
@@ -113,58 +102,69 @@ public class CraftMetaCompass extends CraftMetaItem implements CompassMeta {
 
     @Override
     public boolean hasLodestone() {
-        return this.lodestoneWorld != null;
+        return this.tracker != null && this.tracker.target().isPresent(); // Paper - use LodestoneTracker type
     }
 
     @Override
     public Location getLodestone() {
-        if (this.lodestoneWorld == null) {
+        if (this.tracker == null || this.tracker.target().isEmpty()) { // Paper - use LodestoneTracker type
             return null;
         }
-        ServerLevel worldServer = MinecraftServer.getServer().getLevel(this.lodestoneWorld);
+        ServerLevel worldServer = MinecraftServer.getServer().getLevel(this.tracker.target().get().dimension()); // Paper - use LodestoneTracker type
         World world = worldServer != null ? worldServer.getWorld() : null;
-        return new Location(world, this.lodestoneX, this.lodestoneY, this.lodestoneZ); // world may be null here, if the referenced world is not loaded
+        return org.bukkit.craftbukkit.util.CraftLocation.toBukkit(this.tracker.target().get().pos(), world); // world may be null here, if the referenced world is not loaded // Paper - use LodestoneTracker type
     }
 
     @Override
     public void setLodestone(Location lodestone) {
         Preconditions.checkArgument(lodestone == null || lodestone.getWorld() != null, "world is null");
         if (lodestone == null) {
-            this.lodestoneWorld = null;
+            // Paper start - use LodestoneTracker type
+            if (this.tracker != null) {
+                this.tracker = new LodestoneTracker(java.util.Optional.empty(), this.tracker.tracked()); // Paper - use LodestoneTracker type
+            }
+            // Paper end - use LodestoneTracker type
         } else {
-            this.lodestoneWorld = ((CraftWorld) lodestone.getWorld()).getHandle().dimension();
+            // Paper start - use LodestoneTracker type
-            this.lodestoneX = lodestone.getBlockX();
+            GlobalPos pos = GlobalPos.of(
-            this.lodestoneY = lodestone.getBlockY();
+                ((CraftWorld) lodestone.getWorld()).getHandle().dimension(),
-            this.lodestoneZ = lodestone.getBlockZ();
+                io.papermc.paper.util.MCUtil.toBlockPosition(lodestone)
+            );
+            boolean tracked = this.tracker == null || this.tracker.tracked();
+            this.tracker = new LodestoneTracker(Optional.of(pos), tracked);
+            // Paper end - use LodestoneTracker type
         }
     }
 
-    boolean hasLodestoneTracked() {
-        return !this.tracked;
-    }
-
     @Override
     public boolean isLodestoneTracked() {
-        return this.tracked;
+        return this.tracker != null && this.tracker.tracked(); // Paper - use LodestoneTracker type
     }
 
     @Override
     public void setLodestoneTracked(boolean tracked) {
-        this.tracked = tracked;
+        final Optional<GlobalPos> trackedPos = this.tracker != null ? this.tracker.target() : Optional.empty(); // Paper - use LodestoneTracker type
+        this.tracker = new LodestoneTracker(trackedPos, tracked); // Paper - use LodestoneTracker type
     }
 
+    // Paper start - Add more lodestone compass methods
+    @Override
+    public boolean isLodestoneCompass() {
+        return this.tracker != null;
+    }
+
+    @Override
+    public void clearLodestone() {
+        this.tracker = null;
+    }
+    // Paper end - Add more lodestone compass methods
+
     @Override
     int applyHash() {
         final int original;
         int hash = original = super.applyHash();
-        if (this.hasLodestone()) {
+        if (this.isLodestoneCompass()) {
-            hash = 73 * hash + this.lodestoneWorld.hashCode();
+            hash = 73 * hash + this.tracker.hashCode(); // Paper - use LodestoneTracker type
-            hash = 73 * hash + this.lodestoneX;
-            hash = 73 * hash + this.lodestoneY;
-            hash = 73 * hash + this.lodestoneZ;
-        }
-        if (this.hasLodestoneTracked()) {
-            hash = 73 * hash + (this.isLodestoneTracked() ? 1231 : 1237);
         }
 
         return original != hash ? CraftMetaCompass.class.hashCode() ^ hash : hash;
@@ -178,10 +178,7 @@ public class CraftMetaCompass extends CraftMetaItem implements CompassMeta {
         if (meta instanceof CraftMetaCompass) {
             CraftMetaCompass that = (CraftMetaCompass) meta;
 
-            return (this.hasLodestone() ? that.hasLodestone() && this.lodestoneWorld.equals(that.lodestoneWorld)
+            return java.util.Objects.equals(this.tracker, that.tracker); // Paper - use LodestoneTracker type
-                    && this.lodestoneX == that.lodestoneX && this.lodestoneY == that.lodestoneY
-                    && this.lodestoneZ == that.lodestoneZ : !that.hasLodestone())
-                    && this.tracked == that.tracked;
         }
         return true;
     }
@@ -195,14 +192,16 @@ public class CraftMetaCompass extends CraftMetaItem implements CompassMeta {
     Builder<String, Object> serialize(Builder<String, Object> builder) {
         super.serialize(builder);
 
-        if (this.hasLodestone()) {
+        if (this.isLodestoneCompass()) { // Paper - use LodestoneTracker type
-            builder.put(CraftMetaCompass.LODESTONE_POS_WORLD.BUKKIT, this.lodestoneWorld.location().toString());
+            // Paper start - use LodestoneTracker type
-            builder.put(CraftMetaCompass.LODESTONE_POS_X.BUKKIT, this.lodestoneX);
+            if (this.tracker.target().isPresent()) {
-            builder.put(CraftMetaCompass.LODESTONE_POS_Y.BUKKIT, this.lodestoneY);
+                builder.put(CraftMetaCompass.LODESTONE_POS_WORLD.BUKKIT, this.tracker.target().get().dimension().location().toString());
-            builder.put(CraftMetaCompass.LODESTONE_POS_Z.BUKKIT, this.lodestoneZ);
+                builder.put(CraftMetaCompass.LODESTONE_POS_X.BUKKIT, this.tracker.target().get().pos().getX());
+                builder.put(CraftMetaCompass.LODESTONE_POS_Y.BUKKIT, this.tracker.target().get().pos().getY());
+                builder.put(CraftMetaCompass.LODESTONE_POS_Z.BUKKIT, this.tracker.target().get().pos().getZ());
             }
-        if (this.hasLodestoneTracked()) {
+            builder.put(CraftMetaCompass.LODESTONE_TRACKED.BUKKIT, this.tracker.tracked());
-            builder.put(CraftMetaCompass.LODESTONE_TRACKED.BUKKIT, this.tracked);
+            // Paper end - use LodestoneTracker type
         }
 
         return builder;

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaCrossbow.java

@@ -117,7 +117,7 @@ public class CraftMetaCrossbow extends CraftMetaItem implements CrossbowMeta {
     @Override
     public void addChargedProjectile(ItemStack item) {
         Preconditions.checkArgument(item != null, "item");
-        Preconditions.checkArgument(item.getType() == Material.FIREWORK_ROCKET || CraftItemType.bukkitToMinecraft(item.getType()) instanceof ArrowItem, "Item %s is not an arrow or firework rocket", item);
+        Preconditions.checkArgument(!item.isEmpty(), "Item cannot be empty"); // Paper
 
         if (this.chargedProjectiles == null) {
             this.chargedProjectiles = new ArrayList<>();

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaEntityTag.java

@@ -98,7 +98,7 @@ public class CraftMetaEntityTag extends CraftMetaItem {
         if (meta instanceof CraftMetaEntityTag) {
             CraftMetaEntityTag that = (CraftMetaEntityTag) meta;
 
-            return this.entityTag != null ? that.entityTag != null && this.entityTag.equals(that.entityTag) : this.entityTag == null;
+            return this.entityTag != null ? that.entityTag != null && this.entityTag.equals(that.entityTag) : that.entityTag == null; // Paper
         }
         return true;
     }

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaFirework.java

@@ -55,7 +55,7 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
 
         this.power = that.power;
 
-        if (that.hasEffects()) {
+        if (that.effects != null) { // Paper
             this.effects = new ArrayList<>(that.effects);
         }
     }
@@ -88,7 +88,7 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
         }
 
         Iterable<?> effects = SerializableMeta.getObject(Iterable.class, map, CraftMetaFirework.EXPLOSIONS.BUKKIT, true);
-        this.safelyAddEffects(effects);
+        this.safelyAddEffects(effects, false); // Paper - limit firework effects
     }
 
     static FireworkEffect getEffect(FireworkExplosion explosion) {
@@ -98,19 +98,14 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
                 .with(CraftMetaFirework.getEffectType(explosion.shape()));
 
         IntList colors = explosion.colors();
-        // People using buggy command generators specify a list rather than an int here, so recover with dummy data.
+        // Paper - this is no longer needed
-        // Wrong: Colors: [1234]
-        // Right: Colors: [I;1234]
-        if (colors.isEmpty()) {
-            effect.withColor(Color.WHITE);
-        }
 
         for (int color : colors) {
-            effect.withColor(Color.fromRGB(color));
+            effect.withColor(Color.fromRGB(color & 0xFFFFFF)); // Paper - try to keep color component consistent with vanilla (top byte is ignored), this will however change the color component for out of bound color
         }
 
         for (int color : explosion.fadeColors()) {
-            effect.withFade(Color.fromRGB(color));
+            effect.withFade(Color.fromRGB(color & 0xFFFFFF)); // Paper
         }
 
         return effect.build();
@@ -162,7 +157,7 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
         return !(this.effects == null || this.effects.isEmpty());
     }
 
-    void safelyAddEffects(Iterable<?> collection) {
+    void safelyAddEffects(Iterable<?> collection, final boolean throwOnOversize) { // Paper
         if (collection == null || (collection instanceof Collection && ((Collection<?>) collection).isEmpty())) {
             return;
         }
@@ -174,6 +169,15 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
 
         for (Object obj : collection) {
             Preconditions.checkArgument(obj instanceof FireworkEffect, "%s in %s is not a FireworkEffect", obj, collection);
+            // Paper start - limit firework effects
+            if (effects.size() + 1 > Fireworks.MAX_EXPLOSIONS) {
+                if (throwOnOversize) {
+                    throw new IllegalArgumentException("Cannot have more than " + Fireworks.MAX_EXPLOSIONS + " firework effects");
+                } else {
+                    continue;
+                }
+            }
+            // Paper end - limit firework effects
             effects.add((FireworkEffect) obj);
         }
     }
@@ -215,7 +219,7 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
     }
 
     boolean isFireworkEmpty() {
-        return !(this.hasEffects() || this.hasPower());
+        return !(this.effects != null || this.hasPower()); // Paper - empty effects list should stay on the item
     }
 
     @Override
@@ -232,7 +236,7 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
         if (meta instanceof CraftMetaFirework that) {
 
             return (Objects.equals(this.power, that.power))
-                    && (this.hasEffects() ? that.hasEffects() && this.effects.equals(that.effects) : !that.hasEffects());
+                    && (this.effects != null ? that.effects != null && this.effects.equals(that.effects) : that.effects == null); // Paper
         }
 
         return true;
@@ -250,7 +254,7 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
         if (this.hasPower()) {
             hash = 61 * hash + this.power;
         }
-        if (this.hasEffects()) {
+        if (this.effects != null) { // Paper
             hash = 61 * hash + 13 * this.effects.hashCode();
         }
         return hash != original ? CraftMetaFirework.class.hashCode() ^ hash : hash;
@@ -260,7 +264,7 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
     Builder<String, Object> serialize(Builder<String, Object> builder) {
         super.serialize(builder);
 
-        if (this.hasEffects()) {
+        if (this.effects != null) { // Paper
             builder.put(CraftMetaFirework.EXPLOSIONS.BUKKIT, ImmutableList.copyOf(this.effects));
         }
 
@@ -285,6 +289,7 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
     @Override
     public void addEffect(FireworkEffect effect) {
         Preconditions.checkArgument(effect != null, "FireworkEffect cannot be null");
+        Preconditions.checkArgument(this.effects == null || this.effects.size() + 1 <= Fireworks.MAX_EXPLOSIONS, "cannot have more than %s firework effects", Fireworks.MAX_EXPLOSIONS); // Paper - limit firework effects
         if (this.effects == null) {
             this.effects = new ArrayList<FireworkEffect>();
         }
@@ -294,6 +299,10 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
     @Override
     public void addEffects(FireworkEffect... effects) {
         Preconditions.checkArgument(effects != null, "effects cannot be null");
+        // Paper start - limit firework effects
+        final int initialSize = this.effects == null ? 0 : this.effects.size();
+        Preconditions.checkArgument(initialSize + effects.length <= Fireworks.MAX_EXPLOSIONS, "Cannot have more than %s firework effects", Fireworks.MAX_EXPLOSIONS);
+        // Paper end - limit firework effects
         if (effects.length == 0) {
             return;
         }
@@ -312,7 +321,7 @@ class CraftMetaFirework extends CraftMetaItem implements FireworkMeta {
     @Override
     public void addEffects(Iterable<FireworkEffect> effects) {
         Preconditions.checkArgument(effects != null, "effects cannot be null");
-        this.safelyAddEffects(effects);
+        this.safelyAddEffects(effects, true); // Paper - limit firework effects
     }
 
     @Override

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaItem.java

@@ -201,9 +201,10 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
         }
     }
 
-    static final class Applicator {
+    static abstract class Applicator { // Paper - support updating profile after resolving it
 
-        private final DataComponentPatch.Builder builder = DataComponentPatch.builder();
+        final DataComponentPatch.Builder builder = DataComponentPatch.builder(); // Paper - private -> package-private
+        void skullCallback(net.minecraft.world.item.component.ResolvableProfile resolvableProfile) {} // Paper - support updating profile after resolving it
 
         <T> Applicator put(ItemMetaKeyType<T> key, T value) {
             this.builder.set(key.TYPE, value);
@@ -310,7 +311,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     private CraftToolComponent tool;
     private CraftEquippableComponent equippable;
     private CraftJukeboxComponent jukebox;
-    private int damage;
+    private Integer damage; // Paper - may not be set
     private Integer maxDamage;
 
     private static final Set<DataComponentType> HANDLED_TAGS = Sets.newHashSet();
@@ -345,7 +346,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
             this.enchantments = new EnchantmentMap(meta.enchantments); // Paper
         }
 
-        if (meta.hasAttributeModifiers()) {
+        if (meta.attributeModifiers != null) { // Paper
             this.attributeModifiers = LinkedHashMultimap.create(meta.attributeModifiers);
         }
 
@@ -394,6 +395,11 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     }
 
     CraftMetaItem(DataComponentPatch tag, Set<DataComponentType<?>> extraHandledTags) { // Paper - improve handled tags on type changes
+        // Paper start - properly support data components in BlockEntity
+        this.updateFromPatch(tag, extraHandledTags);
+    }
+    protected final void updateFromPatch(DataComponentPatch tag, Set<DataComponentType<?>> extraHandledTags) {
+        // Paper end - properly support data components in BlockEntity
         CraftMetaItem.getOrEmpty(tag, CraftMetaItem.NAME).ifPresent((component) -> {
             this.displayName = component;
         });
@@ -912,7 +918,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
         Map<?, ?> mods = SerializableMeta.getObject(Map.class, map, key.BUKKIT, true);
         Multimap<Attribute, AttributeModifier> result = LinkedHashMultimap.create();
         if (mods == null) {
-            return result;
+            return null; // Paper - null is different from an empty map
         }
 
         for (Object obj : mods.keySet()) {
@@ -1043,7 +1049,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
             itemTag.put(CraftMetaItem.JUKEBOX_PLAYABLE, this.jukebox.getHandle());
         }
 
-        if (this.hasDamage()) {
+        if (this.hasDamageValue()) { // Paper - preserve empty/0 damage
             itemTag.put(CraftMetaItem.DAMAGE, this.damage);
         }
 
@@ -1093,7 +1099,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     }
 
     void applyEnchantments(Map<Enchantment, Integer> enchantments, CraftMetaItem.Applicator tag, ItemMetaKeyType<ItemEnchantments> key, ItemFlag itemFlag) {
-        if (enchantments == null && !this.hasItemFlag(itemFlag)) {
+        if (enchantments == null /*&& !this.hasItemFlag(itemFlag)*/) { // Paper - general item meta fixes - only emit enchantment component if enchantments are defined
             return;
         }
 
@@ -1110,10 +1116,8 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     }
 
     void applyModifiers(Multimap<Attribute, AttributeModifier> modifiers, CraftMetaItem.Applicator tag) {
-        if (modifiers == null || modifiers.isEmpty()) {
+        if (modifiers == null/* || modifiers.isEmpty()*/) { // Paper - empty modifiers has a specific meaning, they should still be saved
-            if (this.hasItemFlag(ItemFlag.HIDE_ATTRIBUTES)) {
+            // Paper - don't save ItemFlag if the underlying data isn't present
-                tag.put(CraftMetaItem.ATTRIBUTES, new ItemAttributeModifiers(Collections.emptyList(), false));
-            }
             return;
         }
 
@@ -1150,7 +1154,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
 
     @Overridden
     boolean isEmpty() {
-        return !(this.hasDisplayName() || this.hasItemName() || this.hasLocalizedName() || this.hasEnchants() || (this.lore != null) || this.hasCustomModelData() || this.hasEnchantable() || this.hasBlockData() || this.hasRepairCost() || !this.unhandledTags.build().isEmpty() || !this.removedTags.isEmpty() || !this.persistentDataContainer.isEmpty() || this.hideFlag != 0 || this.isHideTooltip() || this.hasTooltipStyle() || this.hasItemModel() || this.isUnbreakable() || this.hasEnchantmentGlintOverride() || this.isGlider() || this.hasDamageResistant() || this.hasMaxStackSize() || this.hasRarity() || this.hasUseRemainder() || this.hasUseCooldown() || this.hasFood() || this.hasTool() || this.hasJukeboxPlayable() || this.hasEquippable() || this.hasDamage() || this.hasMaxDamage() || this.hasAttributeModifiers() || this.customTag != null || this.canPlaceOnPredicates != null || this.canBreakPredicates != null); // Paper
+        return !(this.hasDisplayName() || this.hasItemName() || this.hasLocalizedName() || this.hasEnchants() || (this.lore != null) || this.hasCustomModelData() || this.hasEnchantable() || this.hasBlockData() || this.hasRepairCost() || !this.unhandledTags.build().isEmpty() || !this.removedTags.isEmpty() || !this.persistentDataContainer.isEmpty() || this.hideFlag != 0 || this.isHideTooltip() || this.hasTooltipStyle() || this.hasItemModel() || this.isUnbreakable() || this.hasEnchantmentGlintOverride() || this.isGlider() || this.hasDamageResistant() || this.hasMaxStackSize() || this.hasRarity() || this.hasUseRemainder() || this.hasUseCooldown() || this.hasFood() || this.hasTool() || this.hasJukeboxPlayable() || this.hasEquippable() || this.hasDamageValue() || this.hasMaxDamage() || this.hasAttributeModifiers() || this.customTag != null || this.canPlaceOnPredicates != null || this.canBreakPredicates != null); // Paper
     }
 
     // Paper start
@@ -1246,6 +1250,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
 
     @Override
     public void lore(final List<? extends net.kyori.adventure.text.Component> lore) {
+        Preconditions.checkArgument(lore == null || lore.size() <= ItemLore.MAX_LINES, "lore cannot have more than %s lines", ItemLore.MAX_LINES); // Paper - limit lore lines
         this.lore = lore != null ? io.papermc.paper.adventure.PaperAdventure.asVanilla(lore) : null;
     }
     // Paper end
@@ -1304,7 +1309,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     @Override
     public void removeEnchantments() {
         if (this.hasEnchants()) {
-            this.enchantments.clear();
+            this.enchantments = null; // Paper - Correctly clear enchantments
         }
     }
 
@@ -1370,6 +1375,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     // Paper end
     @Override
     public void setLore(List<String> lore) {
+        Preconditions.checkArgument(lore == null || lore.size() <= ItemLore.MAX_LINES, "lore cannot have more than %s lines", ItemLore.MAX_LINES); // Paper - limit lore lines
         if (lore == null || lore.isEmpty()) {
             this.lore = null;
         } else {
@@ -1385,6 +1391,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     // Paper start
     @Override
     public void setLoreComponents(List<net.md_5.bungee.api.chat.BaseComponent[]> lore) {
+        Preconditions.checkArgument(lore == null || lore.size() <= ItemLore.MAX_LINES, "lore cannot have more than %s lines", ItemLore.MAX_LINES); // Paper - limit lore lines
         if (lore == null) {
             this.lore = null;
         } else {
@@ -1439,6 +1446,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
 
     @Override
     public void setEnchantable(Integer data) {
+        Preconditions.checkArgument(data == null || data > 0, "Enchantability must be positive"); // Paper
         this.enchantableValue = data;
     }
 
@@ -1615,6 +1623,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
 
     @Override
     public void setUseRemainder(ItemStack useRemainder) {
+        Preconditions.checkArgument(useRemainder == null || !useRemainder.isEmpty(), "Item cannot be empty"); // Paper
         this.useRemainder = useRemainder;
     }
 
@@ -1711,7 +1720,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
 
     @Override
     public Multimap<Attribute, AttributeModifier> getAttributeModifiers(@Nullable EquipmentSlot slot) {
-        this.checkAttributeList();
+        if (this.attributeModifiers == null) return LinkedHashMultimap.create(); // Paper - don't change the components
         SetMultimap<Attribute, AttributeModifier> result = LinkedHashMultimap.create();
         for (Map.Entry<Attribute, AttributeModifier> entry : this.attributeModifiers.entries()) {
             if (entry.getValue().getSlot() == null || entry.getValue().getSlot() == slot) {
@@ -1724,6 +1733,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     @Override
     public Collection<AttributeModifier> getAttributeModifiers(@Nonnull Attribute attribute) {
         Preconditions.checkNotNull(attribute, "Attribute cannot be null");
+        if (this.attributeModifiers == null) return null; // Paper - fix NPE
         return this.attributeModifiers.containsKey(attribute) ? ImmutableList.copyOf(this.attributeModifiers.get(attribute)) : null;
     }
 
@@ -1731,22 +1741,33 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     public boolean addAttributeModifier(@Nonnull Attribute attribute, @Nonnull AttributeModifier modifier) {
         Preconditions.checkNotNull(attribute, "Attribute cannot be null");
         Preconditions.checkNotNull(modifier, "AttributeModifier cannot be null");
-        this.checkAttributeList();
+        if (this.attributeModifiers != null) { // Paper
         for (Map.Entry<Attribute, AttributeModifier> entry : this.attributeModifiers.entries()) {
             Preconditions.checkArgument(!(entry.getValue().getKey().equals(modifier.getKey()) && entry.getKey() == attribute), "Cannot register AttributeModifier. Modifier is already applied! %s", modifier); // Paper - attribute modifiers with same namespaced key but on different attributes are fine
         }
+        } // Paper
+        this.checkAttributeList(); // Paper - moved down
         return this.attributeModifiers.put(attribute, modifier);
     }
 
     @Override
     public void setAttributeModifiers(@Nullable Multimap<Attribute, AttributeModifier> attributeModifiers) {
-        if (attributeModifiers == null || attributeModifiers.isEmpty()) {
+        // Paper start - distinguish between null and empty
+        if (attributeModifiers == null) {
+            this.attributeModifiers = null;
+            return;
+        }
+        if (attributeModifiers.isEmpty()) {
+            // Paper end - distinguish between null and empty
             this.attributeModifiers = LinkedHashMultimap.create();
             return;
         }
 
-        this.checkAttributeList();
+        // Paper start - fix modifiers meta
+        if (this.attributeModifiers != null) {
             this.attributeModifiers.clear();
+        }
+        // Paper end
 
         Iterator<Map.Entry<Attribute, AttributeModifier>> iterator = attributeModifiers.entries().iterator();
         while (iterator.hasNext()) {
@@ -1756,6 +1777,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
                 iterator.remove();
                 continue;
             }
+            this.checkAttributeList(); // Paper - moved down
             this.attributeModifiers.put(next.getKey(), next.getValue());
         }
     }
@@ -1763,13 +1785,13 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     @Override
     public boolean removeAttributeModifier(@Nonnull Attribute attribute) {
         Preconditions.checkNotNull(attribute, "Attribute cannot be null");
-        this.checkAttributeList();
+        if (this.attributeModifiers == null) return false; // Paper
         return !this.attributeModifiers.removeAll(attribute).isEmpty();
     }
 
     @Override
     public boolean removeAttributeModifier(@Nullable EquipmentSlot slot) {
-        this.checkAttributeList();
+        if (this.attributeModifiers == null) return false; // Paper
         int removed = 0;
         Iterator<Map.Entry<Attribute, AttributeModifier>> iter = this.attributeModifiers.entries().iterator();
 
@@ -1789,7 +1811,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     public boolean removeAttributeModifier(@Nonnull Attribute attribute, @Nonnull AttributeModifier modifier) {
         Preconditions.checkNotNull(attribute, "Attribute cannot be null");
         Preconditions.checkNotNull(modifier, "AttributeModifier cannot be null");
-        this.checkAttributeList();
+        if (this.attributeModifiers == null) return false; // Paper
         int removed = 0;
         Iterator<Map.Entry<Attribute, AttributeModifier>> iter = this.attributeModifiers.entries().iterator();
 
@@ -1811,7 +1833,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
 
     @Override
     public String getAsString() {
-        CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator();
+        CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator() {}; // Paper - support updating profile after resolving it
         this.applyToItem(tag);
         DataComponentPatch patch = tag.build();
         net.minecraft.nbt.Tag nbt = DataComponentPatch.CODEC.encodeStart(MinecraftServer.getDefaultRegistryAccess().createSerializationContext(NbtOps.INSTANCE), patch).getOrThrow();
@@ -1820,7 +1842,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
 
     @Override
     public String getAsComponentString() {
-        CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator();
+        CraftMetaItem.Applicator tag = new CraftMetaItem.Applicator() {}; // Paper
         this.applyToItem(tag);
         DataComponentPatch patch = tag.build();
 
@@ -1860,6 +1882,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
         if (first == null || second == null) {
             return false;
         }
+        if (first.isEmpty() && second.isEmpty()) return true; // Paper - empty modifiers are equivalent
         for (Map.Entry<Attribute, AttributeModifier> entry : first.entries()) {
             if (!second.containsEntry(entry.getKey(), entry.getValue())) {
                 return false;
@@ -1875,19 +1898,33 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
 
     @Override
     public boolean hasDamage() {
-        return this.damage > 0;
+        return this.damage != null && this.damage > 0; // Paper - null check
     }
 
     @Override
     public int getDamage() {
-        return this.damage;
+        return this.damage == null ? 0 : this.damage; // Paper - null check
     }
 
     @Override
     public void setDamage(int damage) {
+        Preconditions.checkArgument(damage >= 0, "Damage cannot be negative"); // Paper
+        Preconditions.checkArgument(!this.hasMaxDamage() || damage <= this.maxDamage, "Damage cannot exceed max damage"); // Paper
         this.damage = damage;
     }
 
+    // Paper start - preserve empty/0 damage
+    @Override
+    public boolean hasDamageValue() {
+        return this.damage != null;
+    }
+
+    @Override
+    public void resetDamage() {
+        this.damage = null;
+    }
+    // Paper end - preserve empty/0 damage
+
     @Override
     public boolean hasMaxDamage() {
         return this.maxDamage != null;
@@ -1901,6 +1938,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
 
     @Override
     public void setMaxDamage(Integer maxDamage) {
+        Preconditions.checkArgument(maxDamage == null || maxDamage > 0, "Max damage should be positive"); // Paper
         this.maxDamage = maxDamage;
     }
 
@@ -1933,7 +1971,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
                 && (this.hasEnchantable() ? that.hasEnchantable() && this.enchantableValue.equals(that.enchantableValue) : !that.hasEnchantable())
                 && (this.hasBlockData() ? that.hasBlockData() && this.blockData.equals(that.blockData) : !that.hasBlockData())
                 && (this.hasRepairCost() ? that.hasRepairCost() && this.repairCost == that.repairCost : !that.hasRepairCost())
-                && (this.hasAttributeModifiers() ? that.hasAttributeModifiers() && CraftMetaItem.compareModifiers(this.attributeModifiers, that.attributeModifiers) : !that.hasAttributeModifiers())
+                && (this.attributeModifiers != null ? that.attributeModifiers != null && CraftMetaItem.compareModifiers(this.attributeModifiers, that.attributeModifiers) : that.attributeModifiers == null) // Paper - track only null modifiers
                 && (this.unhandledTags.equals(that.unhandledTags))
                 && (this.removedTags.equals(that.removedTags))
                 && (Objects.equals(this.customTag, that.customTag))
@@ -1954,7 +1992,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
                 && (this.hasTool() ? that.hasTool() && this.tool.equals(that.tool) : !that.hasTool())
                 && (this.hasEquippable() ? that.hasEquippable() && this.equippable.equals(that.equippable) : !that.hasEquippable())
                 && (this.hasJukeboxPlayable() ? that.hasJukeboxPlayable() && this.jukebox.equals(that.jukebox) : !that.hasJukeboxPlayable())
-                && (this.hasDamage() ? that.hasDamage() && this.damage == that.damage : !that.hasDamage())
+                && (Objects.equals(this.damage, that.damage)) // Paper - preserve empty/0 damage
                 && (this.hasMaxDamage() ? that.hasMaxDamage() && this.maxDamage.equals(that.maxDamage) : !that.hasMaxDamage())
                 && (this.canPlaceOnPredicates != null ? that.canPlaceOnPredicates != null && this.canPlaceOnPredicates.equals(that.canPlaceOnPredicates) : that.canPlaceOnPredicates == null) // Paper
                 && (this.canBreakPredicates != null ? that.canBreakPredicates != null && this.canBreakPredicates.equals(that.canBreakPredicates) : that.canBreakPredicates == null) // Paper
@@ -2007,9 +2045,9 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
         hash = 61 * hash + (this.hasTool() ? this.tool.hashCode() : 0);
         hash = 61 * hash + (this.hasJukeboxPlayable() ? this.jukebox.hashCode() : 0);
         hash = 61 * hash + (this.hasEquippable() ? this.equippable.hashCode() : 0);
-        hash = 61 * hash + (this.hasDamage() ? this.damage : 0);
+        hash = 61 * hash + (this.hasDamageValue() ? this.damage : -1); // Paper - preserve empty/0 damage
-        hash = 61 * hash + (this.hasMaxDamage() ? 1231 : 1237);
+        hash = 61 * hash + (this.hasMaxDamage() ? this.maxDamage.hashCode() : 0); // Paper - max damage is not a boolean
-        hash = 61 * hash + (this.hasAttributeModifiers() ? this.attributeModifiers.hashCode() : 0);
+        hash = 61 * hash + (this.attributeModifiers != null ? this.attributeModifiers.hashCode() : 0); // Paper - track only null attributes
         hash = 61 * hash + (this.canPlaceOnPredicates != null ? this.canPlaceOnPredicates.hashCode() : 0); // Paper
         hash = 61 * hash + (this.canBreakPredicates != null ? this.canBreakPredicates.hashCode() : 0); // Paper
         hash = 61 * hash + this.version;
@@ -2032,7 +2070,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
             if (this.enchantments != null) {
                 clone.enchantments = new EnchantmentMap(this.enchantments); // Paper
             }
-            if (this.hasAttributeModifiers()) {
+            if (this.attributeModifiers != null) { // Paper
                 clone.attributeModifiers = LinkedHashMultimap.create(this.attributeModifiers);
             }
             if (this.customTag != null) {
@@ -2199,7 +2237,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
             builder.put(CraftMetaItem.JUKEBOX_PLAYABLE.BUKKIT, this.jukebox);
         }
 
-        if (this.hasDamage()) {
+        if (this.hasDamageValue()) { // Paper - preserve empty/0 damage
             builder.put(CraftMetaItem.DAMAGE.BUKKIT, this.damage);
         }
 
@@ -2300,7 +2338,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     }
 
     static void serializeModifiers(Multimap<Attribute, AttributeModifier> modifiers, ImmutableMap.Builder<String, Object> builder, ItemMetaKey key) {
-        if (modifiers == null || modifiers.isEmpty()) {
+        if (modifiers == null/* || modifiers.isEmpty()*/) { // Paper - null and an empty map have different behaviors
             return;
         }
 
@@ -2382,7 +2420,7 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     // Paper start - improve checking handled tags
     @org.jetbrains.annotations.VisibleForTesting
     public static final Map<Class<? extends CraftMetaItem>, Set<DataComponentType<?>>> HANDLED_DCTS_PER_TYPE = new HashMap<>();
-    private static final Set<DataComponentType<?>> DEFAULT_HANDLED_DCTS = Set.of(
+    protected static final Set<DataComponentType<?>> DEFAULT_HANDLED_DCTS = Set.of(
         CraftMetaItem.NAME.TYPE,
         CraftMetaItem.ITEM_NAME.TYPE,
         CraftMetaItem.LORE.TYPE,
@@ -2458,7 +2496,12 @@ class CraftMetaItem implements ItemMeta, Damageable, Repairable, BlockDataMeta {
     // Paper end - improve checking handled data component types
 
     protected static <T> Optional<? extends T> getOrEmpty(DataComponentPatch tag, ItemMetaKeyType<T> type) {
-        Optional<? extends T> result = tag.get(type.TYPE);
+        // Paper start
+        return getOrEmpty(tag, type.TYPE);
+    }
+    protected static <T> Optional<? extends T> getOrEmpty(final DataComponentPatch tag, final DataComponentType<T> type) {
+        Optional<? extends T> result = tag.get(type);
+        // Paper end
 
         return (result != null) ? result : Optional.empty();
     }

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaLeatherArmor.java

@@ -18,16 +18,30 @@ class CraftMetaLeatherArmor extends CraftMetaItem implements LeatherArmorMeta {
 
     static final ItemMetaKeyType<DyedItemColor> COLOR = new ItemMetaKeyType<>(DataComponents.DYED_COLOR, "color");
 
-    private Color color = DEFAULT_LEATHER_COLOR;
+    private Integer color; // Paper - keep color component consistent with vanilla (top byte is ignored)
 
     CraftMetaLeatherArmor(CraftMetaItem meta) {
         super(meta);
-        CraftMetaLeatherArmor.readColor(this, meta);
+        // Paper start
+        if (!(meta instanceof CraftMetaLeatherArmor leatherMeta)) {
+            return;
+        }
+
+        this.color = leatherMeta.color;
+        // Paper end
     }
 
     CraftMetaLeatherArmor(DataComponentPatch tag, java.util.Set<net.minecraft.core.component.DataComponentType<?>> extraHandledDcts) { // Paper
         super(tag, extraHandledDcts); // Paper
-        CraftMetaLeatherArmor.readColor(this, tag);
+        // Paper start
+        getOrEmpty(tag, CraftMetaLeatherArmor.COLOR).ifPresent((dyedItemColor) -> {
+            if (!dyedItemColor.showInTooltip()) {
+                this.addItemFlags(ItemFlag.HIDE_DYE);
+            }
+
+            this.color = dyedItemColor.rgb();
+        });
+        // Paper end
     }
 
     CraftMetaLeatherArmor(Map<String, Object> map) {
@@ -38,7 +52,11 @@ class CraftMetaLeatherArmor extends CraftMetaItem implements LeatherArmorMeta {
     @Override
     void applyToItem(CraftMetaItem.Applicator itemTag) {
         super.applyToItem(itemTag);
-        CraftMetaLeatherArmor.applyColor(this, itemTag);
+        // Paper start
+        if (this.hasColor()) {
+            itemTag.put(CraftMetaLeatherArmor.COLOR, new DyedItemColor(this.color, !this.hasItemFlag(ItemFlag.HIDE_DYE)));
+        }
+        // Paper end
     }
 
     @Override
@@ -66,16 +84,16 @@ class CraftMetaLeatherArmor extends CraftMetaItem implements LeatherArmorMeta {
 
     @Override
     public Color getColor() {
-        return this.color;
+        return this.color == null ? DEFAULT_LEATHER_COLOR : Color.fromRGB(this.color & 0xFFFFFF); // Paper
     }
 
     @Override
     public void setColor(Color color) {
-        this.color = color == null ? DEFAULT_LEATHER_COLOR : color;
+        this.color = color == null ? null : color.asRGB(); // Paper
     }
 
     boolean hasColor() {
-        return CraftMetaLeatherArmor.hasColor(this);
+        return this.color != null; // Paper
     }
 
     @Override
@@ -95,7 +113,7 @@ class CraftMetaLeatherArmor extends CraftMetaItem implements LeatherArmorMeta {
         if (meta instanceof CraftMetaLeatherArmor) {
             CraftMetaLeatherArmor that = (CraftMetaLeatherArmor) meta;
 
-            return this.color.equals(that.color);
+            return this.hasColor() ? that.hasColor() && this.color.equals(that.color) : !that.hasColor(); // Paper - allow null
         }
         return true;
     }
@@ -115,14 +133,16 @@ class CraftMetaLeatherArmor extends CraftMetaItem implements LeatherArmorMeta {
         return original != hash ? CraftMetaLeatherArmor.class.hashCode() ^ hash : hash;
     }
 
+    @io.papermc.paper.annotation.DoNotUse // Paper
     static void readColor(LeatherArmorMeta meta, CraftMetaItem other) {
         if (!(other instanceof CraftMetaLeatherArmor armorMeta)) {
             return;
         }
 
-        meta.setColor(armorMeta.color);
+        // meta.setColor(armorMeta.color); // Paper - commented out, color is now an integer and cannot be passed to setColor
     }
 
+    @io.papermc.paper.annotation.DoNotUse // Paper
     static void readColor(LeatherArmorMeta meta, DataComponentPatch tag) {
         getOrEmpty(tag, CraftMetaLeatherArmor.COLOR).ifPresent((dyedItemColor) -> {
             if (!dyedItemColor.showInTooltip()) {
@@ -145,6 +165,7 @@ class CraftMetaLeatherArmor extends CraftMetaItem implements LeatherArmorMeta {
         return !DEFAULT_LEATHER_COLOR.equals(meta.getColor());
     }
 
+    @io.papermc.paper.annotation.DoNotUse // Paper
     static void applyColor(LeatherArmorMeta meta, CraftMetaItem.Applicator tag) {
         if (CraftMetaLeatherArmor.hasColor(meta)) {
             tag.put(CraftMetaLeatherArmor.COLOR, new DyedItemColor(meta.getColor().asRGB(), !meta.hasItemFlag(ItemFlag.HIDE_DYE)));

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaMap.java

@@ -29,7 +29,7 @@ class CraftMetaMap extends CraftMetaItem implements MapMeta {
 
     private Integer mapId;
     private byte scaling = CraftMetaMap.SCALING_EMPTY;
-    private Color color;
+    private Integer color; // Paper - keep color component consistent with vanilla (top byte is ignored)
 
     CraftMetaMap(CraftMetaItem meta) {
         super(meta);
@@ -57,7 +57,7 @@ class CraftMetaMap extends CraftMetaItem implements MapMeta {
 
         getOrEmpty(tag, CraftMetaMap.MAP_COLOR).ifPresent((mapColor) -> {
             try {
-                this.color = Color.fromRGB(mapColor.rgb());
+                this.color = mapColor.rgb(); // Paper
             } catch (IllegalArgumentException ex) {
                 // Invalid colour
             }
@@ -101,7 +101,7 @@ class CraftMetaMap extends CraftMetaItem implements MapMeta {
         }
 
         if (this.hasColor()) {
-            tag.put(CraftMetaMap.MAP_COLOR, new MapItemColor(this.color.asRGB()));
+            tag.put(CraftMetaMap.MAP_COLOR, new MapItemColor(this.color)); // Paper
         }
     }
 
@@ -121,6 +121,7 @@ class CraftMetaMap extends CraftMetaItem implements MapMeta {
 
     @Override
     public int getMapId() {
+        Preconditions.checkState(this.hasMapId(), "Item does not have map associated - check hasMapId() first!"); // Paper - fix NPE
         return this.mapId;
     }
 
@@ -181,12 +182,12 @@ class CraftMetaMap extends CraftMetaItem implements MapMeta {
 
     @Override
     public Color getColor() {
-        return this.color;
+        return this.color == null ? null : Color.fromRGB(this.color & 0xFFFFFF); // Paper
     }
 
     @Override
     public void setColor(Color color) {
-        this.color = color;
+        this.color = color == null ? null : color.asRGB(); // Paper
     }
 
     @Override

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaOminousBottle.java

@@ -70,6 +70,7 @@ public class CraftMetaOminousBottle extends CraftMetaItem implements OminousBott
 
     @Override
     public int getAmplifier() {
+        Preconditions.checkState(this.hasAmplifier(), "'ominous_bottle_amplifier' data component is absent. Check hasAmplifier first!"); // Paper - fix NPE
         return this.ominousBottleAmplifier;
     }
 

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaPotion.java

@@ -38,7 +38,7 @@ class CraftMetaPotion extends CraftMetaItem implements PotionMeta {
 
     private PotionType type;
     private List<PotionEffect> customEffects;
-    private Color color;
+    private Integer color; // Paper - keep color component consistent with vanilla (top byte is ignored)
     private String customName;
 
     CraftMetaPotion(CraftMetaItem meta) {
@@ -63,7 +63,7 @@ class CraftMetaPotion extends CraftMetaItem implements PotionMeta {
 
             potionContents.customColor().ifPresent((customColor) -> {
                 try {
-                    this.color = Color.fromRGB(customColor);
+                    this.color = customColor; // Paper
                 } catch (IllegalArgumentException ex) {
                     // Invalid colour
                 }
@@ -132,7 +132,7 @@ class CraftMetaPotion extends CraftMetaItem implements PotionMeta {
         }
 
         Optional<Holder<Potion>> defaultPotion = (this.hasBasePotionType()) ? Optional.of(CraftPotionType.bukkitToMinecraftHolder(this.type)) : Optional.empty();
-        Optional<Integer> potionColor = (this.hasColor()) ? Optional.of(this.color.asRGB()) : Optional.empty();
+        Optional<Integer> potionColor = (this.hasColor()) ? Optional.of(this.color) : Optional.empty(); // Paper
         Optional<String> customName = Optional.ofNullable(this.customName);
 
         List<MobEffectInstance> effectList = new ArrayList<>();
@@ -297,12 +297,12 @@ class CraftMetaPotion extends CraftMetaItem implements PotionMeta {
 
     @Override
     public Color getColor() {
-        return this.color;
+        return this.color == null ? null : Color.fromRGB(this.color & 0xFFFFFF); // Paper
     }
 
     @Override
     public void setColor(Color color) {
-        this.color = color;
+        this.color = color == null ? null : color.asRGB(); // Paper
     }
 
     @Override
@@ -317,6 +317,7 @@ class CraftMetaPotion extends CraftMetaItem implements PotionMeta {
 
     @Override
     public void setCustomPotionName(String customName) {
+        Preconditions.checkArgument(customName == null || customName.length() <= 32767, "Custom name is longer than 32767 characters");
         this.customName = customName;
     }
 

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaShield.java

@@ -28,17 +28,29 @@ public class CraftMetaShield extends CraftMetaItem implements ShieldMeta, BlockS
 
     static final ItemMetaKeyType<net.minecraft.world.item.DyeColor> BASE_COLOR = new ItemMetaKeyType<>(DataComponents.BASE_COLOR, "Base", "base-color");
 
-    private Banner banner;
+    // Paper start - general item meta fixes - decoupled base colour and patterns
+    private @org.jetbrains.annotations.Nullable List<Pattern> patterns;
+    private @org.jetbrains.annotations.Nullable DyeColor baseColor;
+
+    // An empty pattern list is the same as the default on the Shield item, and will hence not be present in the data components of the stack.
+    private boolean hasPatterns() {
+        return this.patterns != null && !this.patterns.isEmpty();
+    }
+    // Paper end - general item meta fixes - decoupled base colour and patterns
 
     CraftMetaShield(CraftMetaItem meta) {
         super(meta);
 
         if (meta instanceof CraftMetaShield craftMetaShield) {
-            if (craftMetaShield.banner != null) {
+            // Paper start - general item meta fixes - decoupled base colour and patterns
-                this.banner = (Banner) craftMetaShield.banner.copy();
+            if (craftMetaShield.patterns != null) this.patterns = new ArrayList<>(craftMetaShield.getPatterns());
-            }
+            if (craftMetaShield.baseColor != null) this.baseColor = craftMetaShield.baseColor;
+            // Paper end - general item meta fixes - decoupled base colour and patterns
         } else if (meta instanceof CraftMetaBlockState state && state.hasBlockState() && state.getBlockState() instanceof Banner banner) {
-            this.banner = (Banner) banner.copy();
+            // Paper start - general item meta fixes - decoupled base colour and patterns
+            this.patterns = banner.getPatterns();
+            this.baseColor = banner.getBaseColor();
+            // Paper end - general item meta fixes - decoupled base colour and patterns
         }
     }
 
@@ -46,7 +58,7 @@ public class CraftMetaShield extends CraftMetaItem implements ShieldMeta, BlockS
         super(tag, extraHandledDcts); // Paper - improve checking handled tags in item meta
 
         getOrEmpty(tag, CraftMetaShield.BASE_COLOR).ifPresent((color) -> {
-            this.banner = CraftMetaShield.getBlockState(DyeColor.getByWoolData((byte) color.getId()));
+            this.baseColor = DyeColor.getByWoolData((byte) color.getId()); // Paper - general item meta fixes - decoupled base colour and patterns
         });
 
         getOrEmpty(tag, CraftMetaBanner.PATTERNS).ifPresent((entityTag) -> {
@@ -68,7 +80,7 @@ public class CraftMetaShield extends CraftMetaItem implements ShieldMeta, BlockS
 
         String baseColor = SerializableMeta.getString(map, CraftMetaShield.BASE_COLOR.BUKKIT, true);
         if (baseColor != null) {
-            this.banner = CraftMetaShield.getBlockState(DyeColor.valueOf(baseColor));
+            this.baseColor = DyeColor.valueOf(baseColor); // Paper - general item meta fixes - decoupled base colour and patterns
         }
 
         Iterable<?> rawPatternList = SerializableMeta.getObject(Iterable.class, map, CraftMetaBanner.PATTERNS.BUKKIT, true);
@@ -86,13 +98,14 @@ public class CraftMetaShield extends CraftMetaItem implements ShieldMeta, BlockS
     void applyToItem(CraftMetaItem.Applicator tag) {
         super.applyToItem(tag);
 
-        if (this.banner != null) {
+        // Paper start - general item meta fixes - decoupled base colour and patterns
-            tag.put(CraftMetaShield.BASE_COLOR, net.minecraft.world.item.DyeColor.byId(this.banner.getBaseColor().getWoolData()));
+        if (this.baseColor != null) tag.put(CraftMetaShield.BASE_COLOR, net.minecraft.world.item.DyeColor.byId(this.baseColor.getWoolData()));
-
+        if (this.patterns != null && !this.patterns.isEmpty()) {
-            if (this.banner.numberOfPatterns() > 0) {
+            {
+        // Paper end - general item meta fixes - decoupled base colour and patterns
                 List<BannerPatternLayers.Layer> newPatterns = new ArrayList<>();
 
-                for (Pattern p : this.banner.getPatterns()) {
+                for (Pattern p : this.patterns) { // Paper - general item meta fixes - decoupled base colour and patterns
                     newPatterns.add(new BannerPatternLayers.Layer(CraftPatternType.bukkitToMinecraftHolder(p.getPattern()), net.minecraft.world.item.DyeColor.byId(p.getColor().getWoolData())));
                 }
 
@@ -103,108 +116,84 @@ public class CraftMetaShield extends CraftMetaItem implements ShieldMeta, BlockS
 
     @Override
     public List<Pattern> getPatterns() {
-        if (this.banner == null) {
+        if (this.patterns == null) { // Paper - general item meta fixes - decoupled base colour and patterns
             return new ArrayList<>();
         }
 
-        return this.banner.getPatterns();
+        return new ArrayList<>(this.patterns); // Paper - general item meta fixes - decoupled base colour and patterns
     }
 
     @Override
     public void setPatterns(List<Pattern> patterns) {
-        if (this.banner == null) {
+        this.patterns = new ArrayList<>(patterns); // Paper - general item meta fixes - decoupled base colour and patterns
-            if (patterns.isEmpty()) {
-                return;
-            }
-
-            this.banner = CraftMetaShield.getBlockState(null);
-        }
-
-        this.banner.setPatterns(patterns);
     }
 
     @Override
     public void addPattern(Pattern pattern) {
-        if (this.banner == null) {
+        // Paper start - general item meta fixes - decoupled base colour and patterns
-            this.banner = CraftMetaShield.getBlockState(null);
+        if (this.patterns == null) this.patterns = new ArrayList<>();
-        }
+        this.patterns.add(pattern);
-
+        // Paper end - general item meta fixes - decoupled base colour and patterns
-        this.banner.addPattern(pattern);
     }
 
     @Override
     public Pattern getPattern(int i) {
-        if (this.banner == null) {
+        if (this.patterns == null) { // Paper - general item meta fixes - decoupled base colour and patterns
             throw new IndexOutOfBoundsException(i);
         }
 
-        return this.banner.getPattern(i);
+        return this.patterns.get(i); // Paper - general item meta fixes - decoupled base colour and patterns
     }
 
     @Override
     public Pattern removePattern(int i) {
-        if (this.banner == null) {
+        if (this.patterns == null) { // Paper - general item meta fixes - decoupled base colour and patterns
             throw new IndexOutOfBoundsException(i);
         }
 
-        return this.banner.removePattern(i);
+        return this.patterns.remove(i); // Paper - general item meta fixes - decoupled base colour and patterns
     }
 
     @Override
     public void setPattern(int i, Pattern pattern) {
-        if (this.banner == null) {
+        if (this.patterns == null) { // Paper - general item meta fixes - decoupled base colour and patterns
             throw new IndexOutOfBoundsException(i);
         }
 
-        this.banner.setPattern(i, pattern);
+        this.patterns.set(i, pattern); // Paper - general item meta fixes - decoupled base colour and patterns
     }
 
     @Override
     public int numberOfPatterns() {
-        if (this.banner == null) {
+        if (this.patterns == null) { // Paper - general item meta fixes - decoupled base colour and patterns
             return 0;
         }
 
-        return this.banner.numberOfPatterns();
+        return this.patterns.size(); // Paper - general item meta fixes - decoupled base colour and patterns
     }
 
     @Override
     public DyeColor getBaseColor() {
-        if (this.banner == null) {
+        return this.baseColor; // Paper - general item meta fixes - decoupled base colour and patterns
-            return null;
-        }
-
-        return this.banner.getBaseColor();
     }
 
     @Override
     public void setBaseColor(DyeColor baseColor) {
-        if (baseColor == null) {
+        this.baseColor = baseColor; // Paper - general item meta fixes - decoupled base colour and patterns
-            if (this.banner.numberOfPatterns() > 0) {
-                this.banner.setBaseColor(DyeColor.WHITE);
-            } else {
-                this.banner = null;
-            }
-        } else {
-            if (this.banner == null) {
-                this.banner = CraftMetaShield.getBlockState(baseColor);
-            }
-
-            this.banner.setBaseColor(baseColor);
-        }
     }
 
     @Override
     ImmutableMap.Builder<String, Object> serialize(ImmutableMap.Builder<String, Object> builder) {
         super.serialize(builder);
 
-        if (this.banner != null) {
+        // Paper start - general item meta fixes - decoupled base colour and patterns
-            builder.put(CraftMetaShield.BASE_COLOR.BUKKIT, this.banner.getBaseColor().toString());
+        if (this.baseColor != null) {
-
+            builder.put(CraftMetaShield.BASE_COLOR.BUKKIT, this.baseColor.toString());
-            if (this.banner.numberOfPatterns() > 0) {
-                builder.put(CraftMetaBanner.PATTERNS.BUKKIT, this.banner.getPatterns());
         }
+        if (hasPatterns()) {
+            builder.put(CraftMetaBanner.PATTERNS.BUKKIT, this.patterns);
         }
+        // Paper end - general item meta fixes - decoupled base colour and patterns
 
         return builder;
     }
@@ -213,8 +202,13 @@ public class CraftMetaShield extends CraftMetaItem implements ShieldMeta, BlockS
     int applyHash() {
         final int original;
         int hash = original = super.applyHash();
-        if (this.banner != null) {
+        // Paper start - general item meta fixes - decoupled base colour and patterns
-            hash = 61 * hash + this.banner.hashCode();
+        if (this.baseColor != null) {
+            hash = 61 * hash + this.baseColor.hashCode();
+        }
+        if (hasPatterns()) {
+            hash = 61 * hash + this.patterns.hashCode();
+        // Paper end - general item meta fixes - decoupled base colour and patterns
         }
         return original != hash ? CraftMetaShield.class.hashCode() ^ hash : hash;
     }
@@ -225,29 +219,33 @@ public class CraftMetaShield extends CraftMetaItem implements ShieldMeta, BlockS
             return false;
         }
         if (meta instanceof CraftMetaShield that) {
-            return Objects.equal(this.banner, that.banner);
+            return Objects.equal(this.baseColor, that.baseColor) && Objects.equal(this.patterns, that.patterns); // Paper - general item meta fixes - decoupled base colour and patterns
         }
         return true;
     }
 
     @Override
     boolean notUncommon(CraftMetaItem meta) {
-        return super.notUncommon(meta) && (meta instanceof CraftMetaShield || this.banner == null);
+        return super.notUncommon(meta) && (meta instanceof CraftMetaShield || (this.baseColor == null && !hasPatterns())); // Paper - general item meta fixes - decoupled base colour and patterns
     }
 
     @Override
     boolean isEmpty() {
-        return super.isEmpty() && this.banner == null;
+        return super.isEmpty() && this.baseColor == null && !hasPatterns(); // Paper - general item meta fixes - decoupled base colour and patterns
     }
 
     @Override
     public boolean hasBlockState() {
-        return this.banner != null;
+        return this.baseColor != null || hasPatterns(); // Paper - general item meta fixes - decoupled base colour and patterns
     }
 
     @Override
     public BlockState getBlockState() {
-        return (this.banner != null) ? this.banner.copy() : CraftMetaShield.getBlockState(null);
+        // Paper start - general item meta fixes - decoupled base colour and patterns
+        final Banner banner = CraftMetaShield.getBlockState(this.baseColor);
+        if (this.patterns != null) banner.setPatterns(this.patterns);
+        return banner;
+        // Paper end - general item meta fixes - decoupled base colour and patterns
     }
 
     @Override
@@ -255,13 +253,18 @@ public class CraftMetaShield extends CraftMetaItem implements ShieldMeta, BlockS
         Preconditions.checkArgument(blockState != null, "blockState must not be null");
         Preconditions.checkArgument(blockState instanceof Banner, "Invalid blockState");
 
-        this.banner = (Banner) blockState;
+        // Paper start - general item meta fixes - decoupled base colour and patterns
+        final Banner banner = (Banner) blockState;
+        this.baseColor = banner.getBaseColor();
+        this.patterns = banner.getPatterns();
+        // Paper end - general item meta fixes - decoupled base colour and patterns
     }
 
     // Paper start - add method to clear block state
     @Override
     public void clearBlockState() {
-        this.banner = null;
+        this.baseColor = null;
+        this.patterns = null;
     }
     // Paper end - add method to clear block state
 
@@ -275,9 +278,10 @@ public class CraftMetaShield extends CraftMetaItem implements ShieldMeta, BlockS
     @Override
     public CraftMetaShield clone() {
         CraftMetaShield meta = (CraftMetaShield) super.clone();
-        if (this.banner != null) {
+        // Paper start - general item meta fixes - decoupled base colour and patterns
-            meta.banner = (Banner) this.banner.copy();
+        meta.baseColor = this.baseColor;
-        }
+        meta.patterns = this.patterns == null ? null : new ArrayList<>(this.patterns);
+        // Paper start - general item meta fixes - decoupled base colour and patterns
         return meta;
     }
 

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaSkull.java

@@ -112,10 +112,10 @@ class CraftMetaSkull extends CraftMetaItem implements SkullMeta {
             // Fill in textures
             PlayerProfile ownerProfile = new CraftPlayerProfile(this.profile); // getOwnerProfile may return null
             if (ownerProfile.getTextures().isEmpty()) {
-                ownerProfile.update().thenAccept((filledProfile) -> {
+                ownerProfile.update().thenAcceptAsync((filledProfile) -> { // Paper - run on main thread
                     this.setOwnerProfile(filledProfile);
-                    tag.put(CraftMetaSkull.SKULL_PROFILE, this.profile);
+                    tag.skullCallback(this.profile); // Paper - actually set profile on itemstack
-                });
+                }, ((org.bukkit.craftbukkit.CraftServer) org.bukkit.Bukkit.getServer()).getServer()); // Paper - run on main thread
             }
         }
 

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaSpawnEgg.java

@@ -121,6 +121,7 @@ public class CraftMetaSpawnEgg extends CraftMetaItem implements SpawnEggMeta {
 
     @Override
     public EntitySnapshot getSpawnedEntity() {
+        if (this.entityTag == null) return null; // Paper - fix NPE
         return CraftEntitySnapshot.create(this.entityTag);
     }
 
@@ -138,7 +139,7 @@ public class CraftMetaSpawnEgg extends CraftMetaItem implements SpawnEggMeta {
         if (meta instanceof CraftMetaSpawnEgg) {
             CraftMetaSpawnEgg that = (CraftMetaSpawnEgg) meta;
 
-            return this.entityTag != null ? that.entityTag != null && this.entityTag.equals(that.entityTag) : this.entityTag == null;
+            return this.entityTag != null ? that.entityTag != null && this.entityTag.equals(that.entityTag) : that.entityTag == null; // Paper
         }
         return true;
     }

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaTropicalFishBucket.java

@@ -120,6 +120,7 @@ class CraftMetaTropicalFishBucket extends CraftMetaItem implements TropicalFishB
 
     @Override
     public DyeColor getPatternColor() {
+        com.google.common.base.Preconditions.checkState(this.hasVariant(), "This bucket doesn't have variant, check hasVariant first!"); // Paper - fix NPE
         return CraftTropicalFish.getPatternColor(this.variant);
     }
 
@@ -133,6 +134,7 @@ class CraftMetaTropicalFishBucket extends CraftMetaItem implements TropicalFishB
 
     @Override
     public DyeColor getBodyColor() {
+        com.google.common.base.Preconditions.checkState(this.hasVariant(), "This bucket doesn't have variant, check hasVariant first!"); // Paper - fix NPE
         return CraftTropicalFish.getBodyColor(this.variant);
     }
 
@@ -146,6 +148,7 @@ class CraftMetaTropicalFishBucket extends CraftMetaItem implements TropicalFishB
 
     @Override
     public TropicalFish.Pattern getPattern() {
+        com.google.common.base.Preconditions.checkState(this.hasVariant(), "This bucket doesn't have variant, check hasVariant first!"); // Paper - fix NPE
         return CraftTropicalFish.getPattern(this.variant);
     }
 

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/SerializableMeta.java

@@ -173,4 +173,21 @@ public final class SerializableMeta implements ConfigurationSerializable {
 
         return result;
     }
+
+    // Paper start - General ItemMeta Fixes
+    public static <T> java.util.Optional<T> getObjectOptionally(Class<T> clazz, Map<?, ?> map, Object field, boolean nullable) {
+        final Object object = map.get(field);
+
+        if (clazz.isInstance(object)) {
+            return java.util.Optional.of(clazz.cast(object));
+        }
+        if (object == null) {
+            if (!nullable) {
+                throw new NoSuchElementException(map + " does not contain " + field);
+            }
+            return java.util.Optional.empty();
+        }
+        throw new IllegalArgumentException(field + "(" + object + ") is not a valid " + clazz);
+    }
+    // Paper end - General ItemMeta Fixes
 }

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/components/CraftCustomModelDataComponent.java

@@ -67,7 +67,7 @@ public final class CraftCustomModelDataComponent implements CustomModelDataCompo
 
     @Override
     public void setFlags(List<Boolean> flags) {
-        this.handle = new CustomModelData(this.handle.floats(), new ArrayList<>(this.handle.flags()), this.handle.strings(), this.handle.colors());
+        this.handle = new CustomModelData(this.handle.floats(), List.copyOf(flags), this.handle.strings(), this.handle.colors()); // Paper
     }
 
     @Override
@@ -77,7 +77,7 @@ public final class CraftCustomModelDataComponent implements CustomModelDataCompo
 
     @Override
     public void setStrings(List<String> strings) {
-        this.handle = new CustomModelData(this.handle.floats(), this.handle.flags(), new ArrayList<>(this.handle.strings()), this.handle.colors());
+        this.handle = new CustomModelData(this.handle.floats(), this.handle.flags(), List.copyOf(strings), this.handle.colors()); // Paper
     }
 
     @Override
@@ -87,7 +87,7 @@ public final class CraftCustomModelDataComponent implements CustomModelDataCompo
 
     @Override
     public void setColors(List<Color> colors) {
-        this.handle = new CustomModelData(this.handle.floats(), this.handle.flags(), this.handle.strings(), new ArrayList<>(this.handle.colors()));
+        this.handle = new CustomModelData(this.handle.floats(), this.handle.flags(), this.handle.strings(), colors.stream().map(Color::asRGB).toList()); // Paper
     }
 
     @Override

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/components/CraftEquippableComponent.java

@@ -172,7 +172,7 @@ public final class CraftEquippableComponent implements EquippableComponent {
 
     @Override
     public void setAllowedEntities(Tag<EntityType> tag) {
-        Preconditions.checkArgument(tag instanceof CraftEntityTag, "tag must be an entity tag");
+        Preconditions.checkArgument(tag == null || tag instanceof CraftEntityTag, "tag must be an entity tag"); // Paper
 
         this.handle = new Equippable(this.handle.slot(), this.handle.equipSound(), this.handle.assetId(), this.handle.cameraOverlay(),
                 (tag != null) ? Optional.of(((CraftEntityTag) tag).getHandle()) : Optional.empty(),

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/components/CraftToolComponent.java

@@ -106,6 +106,7 @@ public final class CraftToolComponent implements ToolComponent {
     public ToolRule addRule(Material block, Float speed, Boolean correctForDrops) {
         Preconditions.checkArgument(block != null, "block must not be null");
         Preconditions.checkArgument(block.isBlock(), "block must be a block type, given %s", block.getKey());
+        Preconditions.checkArgument(speed == null || speed > 0, "speed must be positive"); // Paper - validate speed
 
         Holder.Reference<Block> nmsBlock = CraftBlockType.bukkitToMinecraft(block).builtInRegistryHolder();
         return this.addRule(HolderSet.direct(nmsBlock), speed, correctForDrops);
@@ -113,6 +114,7 @@ public final class CraftToolComponent implements ToolComponent {
 
     @Override
     public ToolRule addRule(Collection<Material> blocks, Float speed, Boolean correctForDrops) {
+        Preconditions.checkArgument(speed == null || speed > 0, "speed must be positive"); // Paper - validate speed
         List<Holder.Reference<Block>> nmsBlocks = new ArrayList<>(blocks.size());
 
         for (Material material : blocks) {
@@ -126,6 +128,7 @@ public final class CraftToolComponent implements ToolComponent {
     @Override
     public ToolRule addRule(Tag<Material> tag, Float speed, Boolean correctForDrops) {
         Preconditions.checkArgument(tag instanceof CraftBlockTag, "tag must be a block tag");
+        Preconditions.checkArgument(speed == null || speed > 0, "speed must be positive"); // Paper - validate speed
         return this.addRule(((CraftBlockTag) tag).getHandle(), speed, correctForDrops);
     }
 
@@ -258,6 +261,7 @@ public final class CraftToolComponent implements ToolComponent {
 
         @Override
         public void setSpeed(Float speed) {
+            Preconditions.checkArgument(speed == null || speed > 0, "speed must be positive"); // Paper - validate speed
             this.handle = new Tool.Rule(this.handle.blocks(), Optional.ofNullable(speed), this.handle.correctForDrops());
         }
 

paper-server/src/test/java/org/bukkit/craftbukkit/inventory/DeprecatedItemMetaCustomValueTest.java

@@ -94,7 +94,7 @@ public class DeprecatedItemMetaCustomValueTest {
     public void testNBTTagStoring() {
         CraftMetaItem itemMeta = this.createComplexItemMeta();
 
-        CraftMetaItem.Applicator compound = new CraftMetaItem.Applicator();
+        CraftMetaItem.Applicator compound = new CraftMetaItem.Applicator() {}; // Paper
         itemMeta.applyToItem(compound);
 
         assertEquals(itemMeta, new CraftMetaItem(compound.build(), null)); // Paper

paper-server/src/test/java/org/bukkit/craftbukkit/inventory/PersistentDataContainerTest.java

@@ -128,7 +128,7 @@ public class PersistentDataContainerTest {
     public void testNBTTagStoring() {
         CraftMetaItem itemMeta = this.createComplexItemMeta();
 
-        CraftMetaItem.Applicator compound = new CraftMetaItem.Applicator();
+        CraftMetaItem.Applicator compound = new CraftMetaItem.Applicator() {}; // Paper
         itemMeta.applyToItem(compound);
 
         assertEquals(itemMeta, new CraftMetaItem(compound.build(), null)); // Paper
@@ -474,7 +474,7 @@ public class PersistentDataContainerTest {
         assertEquals(List.of(), container.get(PersistentDataContainerTest.requestKey("list"), PersistentDataType.LIST.strings()));
 
         // Write and read the entire container to NBT
-        final CraftMetaItem.Applicator storage = new CraftMetaItem.Applicator();
+        final CraftMetaItem.Applicator storage = new CraftMetaItem.Applicator() {}; // Paper
         craftItem.applyToItem(storage);
 
         final CraftMetaItem readItem = new CraftMetaItem(storage.build(), null); // Paper