Change items to not be nullable in 1.20.5+

With the server and client actually having empty checks in many places now, this simplifies empty checks going forward

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/DataItem.java

@@ -93,7 +93,7 @@ public class DataItem implements Item {
     }
 
     @Override
-    public StructuredDataContainer structuredData() {
+    public StructuredDataContainer dataContainer() {
         throw new UnsupportedOperationException();
     }
 

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/Item.java

@@ -90,7 +90,12 @@ public interface Item {
      */
     void setTag(@Nullable CompoundTag tag);
 
-    StructuredDataContainer structuredData();
+    /**
+     * Returns the data container for item data components.
+     *
+     * @return the data container
+     */
+    StructuredDataContainer dataContainer();
 
     /**
      * Returns a copy of the item.

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/StructuredItem.java

@@ -41,6 +41,11 @@ public class StructuredItem implements Item {
         this.data = data;
     }
 
+    public static StructuredItem empty() {
+        // Data is mutable, create a new item
+        return new StructuredItem(0, 0);
+    }
+
     @Override
     public int identifier() {
         return identifier;
@@ -72,7 +77,7 @@ public class StructuredItem implements Item {
     }
 
     @Override
-    public StructuredDataContainer structuredData() {
+    public StructuredDataContainer dataContainer() {
         return data;
     }
 

api/src/main/java/com/viaversion/viaversion/api/type/types/item/ItemCostType1_20_5.java

@@ -54,7 +54,7 @@ public final class ItemCostType1_20_5 extends Type<Item> {
     public void write(final ByteBuf buffer, final Item object) {
         Types.VAR_INT.writePrimitive(buffer, object.identifier());
         Types.VAR_INT.writePrimitive(buffer, object.amount());
-        dataArrayType.write(buffer, object.structuredData().data().values().toArray(EMPTY_DATA_ARRAY));
+        dataArrayType.write(buffer, object.dataContainer().data().values().toArray(EMPTY_DATA_ARRAY));
     }
 
     public static final class OptionalItemCostType extends OptionalType<Item> {

api/src/main/java/com/viaversion/viaversion/api/type/types/item/ItemType1_20_5.java

@@ -33,7 +33,6 @@ import com.viaversion.viaversion.api.type.Types;
 import io.netty.buffer.ByteBuf;
 import it.unimi.dsi.fastutil.objects.Reference2ObjectOpenHashMap;
 import java.util.Map;
-import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class ItemType1_20_5 extends Type<Item> {
 
@@ -45,10 +44,10 @@ public class ItemType1_20_5 extends Type<Item> {
     }
 
     @Override
-    public @Nullable Item read(final ByteBuf buffer) {
+    public Item read(final ByteBuf buffer) {
         final int amount = Types.VAR_INT.readPrimitive(buffer);
         if (amount <= 0) {
-            return null;
+            return StructuredItem.empty();
         }
 
         final int id = Types.VAR_INT.readPrimitive(buffer);
@@ -81,8 +80,8 @@ public class ItemType1_20_5 extends Type<Item> {
     }
 
     @Override
-    public void write(final ByteBuf buffer, @Nullable final Item object) {
+    public void write(final ByteBuf buffer, final Item object) {
-        if (object == null || object.isEmpty()) {
+        if (object.isEmpty()) {
             Types.VAR_INT.writePrimitive(buffer, 0);
             return;
         }
@@ -90,7 +89,7 @@ public class ItemType1_20_5 extends Type<Item> {
         Types.VAR_INT.writePrimitive(buffer, object.amount());
         Types.VAR_INT.writePrimitive(buffer, object.identifier());
 
-        final Map<StructuredDataKey<?>, StructuredData<?>> data = object.structuredData().data();
+        final Map<StructuredDataKey<?>, StructuredData<?>> data = object.dataContainer().data();
         int valuesSize = 0;
         int markersSize = 0;
         for (final StructuredData<?> value : data.values()) {

common/src/main/java/com/viaversion/viaversion/protocols/v1_20_3to1_20_5/rewriter/BlockItemPacketRewriter1_20_5.java

@@ -88,9 +88,9 @@ import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.data.BannerPatterns1_
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.data.DyeColors;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.data.Enchantments1_20_5;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.data.EquipmentSlots1_20_5;
-import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.data.MaxStackSize1_20_3;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.data.Instruments1_20_3;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.data.MapDecorations1_20_5;
+import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.data.MaxStackSize1_20_3;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.data.PotionEffects1_20_5;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.data.Potions1_20_5;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.data.TrimMaterials1_20_3;
@@ -197,7 +197,7 @@ public final class BlockItemPacketRewriter1_20_5 extends ItemRewriter<Clientboun
                     wrapper.passthrough(Types.TAG); // Title
                     wrapper.passthrough(Types.TAG); // Description
 
-                    Item item = handleNonNullItemToClient(wrapper.user(), wrapper.read(itemType()));
+                    Item item = handleNonEmptyItemToClient(wrapper.user(), wrapper.read(itemType()));
                     wrapper.write(mappedItemType(), item);
 
                     wrapper.passthrough(Types.VAR_INT); // Frame type
@@ -247,7 +247,7 @@ public final class BlockItemPacketRewriter1_20_5 extends ItemRewriter<Clientboun
                 final int blockStateId = wrapper.read(Types.VAR_INT);
                 particle.add(Types.VAR_INT, protocol.getMappingData().getNewBlockStateId(blockStateId));
             } else if (mappings.isItemParticle(particleId)) {
-                final Item item = handleNonNullItemToClient(wrapper.user(), wrapper.read(Types.ITEM1_20_2));
+                final Item item = handleNonEmptyItemToClient(wrapper.user(), wrapper.read(Types.ITEM1_20_2));
                 particle.add(Types1_20_5.ITEM, item);
             } else if (particleId == mappings.id("dust")) {
                 // R, g, b, scale
@@ -301,10 +301,10 @@ public final class BlockItemPacketRewriter1_20_5 extends ItemRewriter<Clientboun
             wrapper.passthrough(Types.VAR_INT); // Container id
             final int size = wrapper.passthrough(Types.VAR_INT);
             for (int i = 0; i < size; i++) {
-                Item input = handleNonNullItemToClient(wrapper.user(), wrapper.read(Types.ITEM1_20_2));
+                Item input = handleNonEmptyItemToClient(wrapper.user(), wrapper.read(Types.ITEM1_20_2));
                 wrapper.write(Types1_20_5.ITEM_COST, input);
 
-                final Item output = handleNonNullItemToClient(wrapper.user(), wrapper.read(Types.ITEM1_20_2));
+                final Item output = handleNonEmptyItemToClient(wrapper.user(), wrapper.read(Types.ITEM1_20_2));
                 wrapper.write(Types1_20_5.ITEM, output);
 
                 final Item secondInput = handleItemToClient(wrapper.user(), wrapper.read(Types.ITEM1_20_2));
@@ -323,12 +323,7 @@ public final class BlockItemPacketRewriter1_20_5 extends ItemRewriter<Clientboun
         final RecipeRewriter1_20_3<ClientboundPacket1_20_3> recipeRewriter = new RecipeRewriter1_20_3<>(protocol) {
             @Override
             protected Item rewrite(final UserConnection connection, @Nullable Item item) {
-                item = super.rewrite(connection, item);
+                return handleNonEmptyItemToClient(connection, item);
-                if (item == null || item.isEmpty()) {
-                    // Does not allow empty items
-                    return new StructuredItem(1, 1);
-                }
-                return item;
             }
         };
         protocol.registerClientbound(ClientboundPackets1_20_3.UPDATE_RECIPES, wrapper -> {
@@ -344,18 +339,21 @@ public final class BlockItemPacketRewriter1_20_5 extends ItemRewriter<Clientboun
         });
     }
 
-    public Item handleNonNullItemToClient(final UserConnection connection, @Nullable Item item) {
+    public Item handleNonEmptyItemToClient(final UserConnection connection, @Nullable Item item) {
         item = handleItemToClient(connection, item);
         // Items are no longer nullable in a few places
-        if (item == null || item.isEmpty()) {
+        if (item.isEmpty()) {
             return new StructuredItem(1, 1);
         }
         return item;
     }
 
     @Override
-    public @Nullable Item handleItemToClient(final UserConnection connection, @Nullable final Item item) {
+    public Item handleItemToClient(final UserConnection connection, @Nullable final Item item) {
-        if (item == null) return null;
+        if (item == null) {
+            // We no longer want null items, always unify them to empty
+            return StructuredItem.empty();
+        }
 
         // Add the original as custom data, to be re-used for creative clients as well
         final CompoundTag tag = item.tag();
@@ -369,15 +367,18 @@ public final class BlockItemPacketRewriter1_20_5 extends ItemRewriter<Clientboun
             // Server can send amounts which are higher than vanilla's default, and 1.20.4 will still accept them,
             // let's use the new added data key to emulate this behavior
             if (structuredItem.amount() > MaxStackSize1_20_3.getMaxStackSize(structuredItem.identifier())) {
-                structuredItem.structuredData().set(StructuredDataKey.MAX_STACK_SIZE, structuredItem.amount());
+                structuredItem.dataContainer().set(StructuredDataKey.MAX_STACK_SIZE, structuredItem.amount());
             }
         }
         return super.handleItemToClient(connection, structuredItem);
     }
 
     @Override
-    public @Nullable Item handleItemToServer(UserConnection connection, @Nullable final Item item) {
+    public @Nullable Item handleItemToServer(UserConnection connection, final Item item) {
-        if (item == null) return null;
+        if (item.isEmpty()) {
+            // Empty to null for the old protocols
+            return null;
+        }
 
         super.handleItemToServer(connection, item);
         return toOldItem(connection, item, DATA_CONVERTER);
@@ -385,7 +386,7 @@ public final class BlockItemPacketRewriter1_20_5 extends ItemRewriter<Clientboun
 
     public Item toOldItem(final UserConnection connection, final Item item, final StructuredDataConverter dataConverter) {
         // Start out with custom data and add the rest on top, or short-curcuit with the original item
-        final StructuredDataContainer data = item.structuredData();
+        final StructuredDataContainer data = item.dataContainer();
         data.setIdLookup(protocol, true);
 
         final StructuredData<CompoundTag> customData = data.getNonEmpty(StructuredDataKey.CUSTOM_DATA);
@@ -405,7 +406,7 @@ public final class BlockItemPacketRewriter1_20_5 extends ItemRewriter<Clientboun
     public Item toStructuredItem(final UserConnection connection, final Item old) {
         final CompoundTag tag = old.tag();
         final StructuredItem item = new StructuredItem(old.identifier(), (byte) old.amount(), new StructuredDataContainer());
-        final StructuredDataContainer data = item.structuredData();
+        final StructuredDataContainer data = item.dataContainer();
         data.setIdLookup(protocol, true);
 
         if (tag == null) {
@@ -453,7 +454,7 @@ public final class BlockItemPacketRewriter1_20_5 extends ItemRewriter<Clientboun
         if (blockEntityTag != null) {
             final CompoundTag clonedTag = blockEntityTag.copy();
             updateBlockEntityTag(connection, data, clonedTag);
-            item.structuredData().set(StructuredDataKey.BLOCK_ENTITY_DATA, clonedTag);
+            item.dataContainer().set(StructuredDataKey.BLOCK_ENTITY_DATA, clonedTag);
         }
 
         final CompoundTag debugProperty = tag.getCompoundTag("DebugProperty");
@@ -1176,14 +1177,13 @@ public final class BlockItemPacketRewriter1_20_5 extends ItemRewriter<Clientboun
             final Item[] items = itemsTag.stream()
                 .limit(256)
                 .map(item -> itemFromTag(connection, item))
-                .filter(Objects::nonNull)
                 .filter(item -> allowEmpty || !item.isEmpty())
                 .toArray(Item[]::new);
             data.set(dataKey, items);
         }
     }
 
-    private @Nullable Item itemFromTag(final UserConnection connection, final CompoundTag item) {
+    private Item itemFromTag(final UserConnection connection, final CompoundTag item) {
         final String id = item.getString("id");
         if (id == null) {
             return null;

common/src/main/java/com/viaversion/viaversion/protocols/v1_20_3to1_20_5/rewriter/ComponentRewriter1_20_5.java

@@ -243,7 +243,7 @@ public class ComponentRewriter1_20_5<C extends ClientboundPacketType> extends Co
                 contentsTag.putString("id", "minecraft:stone");
             }
 
-            final Map<StructuredDataKey<?>, StructuredData<?>> data = structuredItem.structuredData().data();
+            final Map<StructuredDataKey<?>, StructuredData<?>> data = structuredItem.dataContainer().data();
             if (!data.isEmpty()) {
                 final CompoundTag components;
                 try {
@@ -971,7 +971,7 @@ public class ComponentRewriter1_20_5<C extends ClientboundPacketType> extends Co
         } catch (IllegalArgumentException ignored) { // Fallback value
             tag.putInt("count", 1);
         }
-        final Map<StructuredDataKey<?>, StructuredData<?>> components = item.structuredData().data();
+        final Map<StructuredDataKey<?>, StructuredData<?>> components = item.dataContainer().data();
         tag.put("components", toTag(components, true));
     }
 

common/src/main/java/com/viaversion/viaversion/protocols/v1_20_3to1_20_5/rewriter/StructuredDataConverter.java

@@ -709,16 +709,12 @@ public final class StructuredDataConverter {
 
     // Check if item name could be mapped, if not, locate original/backup item id and use it
     static int removeItemBackupTag(final CompoundTag tag, final int unmappedId) {
-        if (unmappedId != -1) {
-            return unmappedId;
-        }
-
         final IntTag itemBackupTag = tag.getIntTag(ITEM_BACKUP_TAG_KEY);
         if (itemBackupTag != null) {
             tag.remove(ITEM_BACKUP_TAG_KEY);
             return itemBackupTag.asInt();
         }
-        return -1;
+        return unmappedId;
     }
 
     private void convertBlockPredicates(final CompoundTag tag, final AdventureModePredicate data, final String key, final int hideFlag) {
@@ -808,7 +804,7 @@ public final class StructuredDataConverter {
                 savedItem.putByte("Count", (byte) item.amount());
 
                 final CompoundTag itemTag = new CompoundTag();
-                for (final StructuredData<?> data : item.structuredData().data().values()) {
+                for (final StructuredData<?> data : item.dataContainer().data().values()) {
                     writeToTag(connection, data, itemTag);
                 }
                 savedItem.put("tag", itemTag);

common/src/main/java/com/viaversion/viaversion/protocols/v1_20_3to1_20_5/storage/AcknowledgedMessagesStorage.java

@@ -20,7 +20,6 @@ package com.viaversion.viaversion.protocols.v1_20_3to1_20_5.storage;
 import com.viaversion.viaversion.api.connection.StorableObject;
 import com.viaversion.viaversion.api.minecraft.ProfileKey;
 import com.viaversion.viaversion.api.protocol.packet.PacketWrapper;
-import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.protocols.v1_20_2to1_20_3.packet.ServerboundPackets1_20_3;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.Protocol1_20_3To1_20_5;

common/src/main/java/com/viaversion/viaversion/rewriter/StructuredItemRewriter.java

@@ -24,7 +24,6 @@ import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.protocol.packet.ClientboundPacketType;
 import com.viaversion.viaversion.api.protocol.packet.ServerboundPacketType;
 import com.viaversion.viaversion.api.type.Type;
-import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class StructuredItemRewriter<C extends ClientboundPacketType, S extends ServerboundPacketType,
     T extends Protocol<C, ?, ?, S>> extends ItemRewriter<C, S, T> {
@@ -38,9 +37,9 @@ public class StructuredItemRewriter<C extends ClientboundPacketType, S extends S
     }
 
     @Override
-    public @Nullable Item handleItemToClient(UserConnection connection, @Nullable Item item) {
+    public Item handleItemToClient(UserConnection connection, Item item) {
-        if (item == null) {
+        if (item.isEmpty()) {
-            return null;
+            return item;
         }
 
         final MappingData mappingData = protocol.getMappingData();
@@ -49,16 +48,16 @@ public class StructuredItemRewriter<C extends ClientboundPacketType, S extends S
                 item.setIdentifier(mappingData.getNewItemId(item.identifier()));
             }
             if (mappingData.getDataComponentSerializerMappings() != null) {
-                item.structuredData().setIdLookup(protocol, true);
+                item.dataContainer().setIdLookup(protocol, true);
             }
         }
         return item;
     }
 
     @Override
-    public @Nullable Item handleItemToServer(UserConnection connection, @Nullable Item item) {
+    public Item handleItemToServer(UserConnection connection, Item item) {
-        if (item == null) {
+        if (item.isEmpty()) {
-            return null;
+            return item;
         }
 
         final MappingData mappingData = protocol.getMappingData();
@@ -67,7 +66,7 @@ public class StructuredItemRewriter<C extends ClientboundPacketType, S extends S
                 item.setIdentifier(mappingData.getOldItemId(item.identifier()));
             }
             if (mappingData.getDataComponentSerializerMappings() != null) {
-                item.structuredData().setIdLookup(protocol, false);
+                item.dataContainer().setIdLookup(protocol, false);
             }
         }
         return item;