Fix: item data -> item mapping lookup

supersedes #6053

Author: onebeastchris

core/src/main/java/org/geysermc/geyser/registry/populator/ItemRegistryPopulator.java

@@ -668,6 +668,10 @@ public static void populate() {
 
             ItemMappings itemMappings = ItemMappings.builder()
                     .items(mappings.toArray(new ItemMapping[0]))
+                    .zeroBlockDefinitionRuntimeId(mappings.stream()
+                        .filter(entry -> entry.isBlock() && entry.getBedrockBlockDefinition().getRuntimeId() == 0)
+                        .map(itemMapping -> itemMapping.getBedrockDefinition().getRuntimeId())
+                        .toArray(Integer[]::new))
                     .creativeItems(creativeItems)
                     .creativeItemGroups(creativeItemGroups)
                     .itemDefinitions(registry)

core/src/main/java/org/geysermc/geyser/registry/type/ItemMappings.java

@@ -31,6 +31,7 @@
 import lombok.Value;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.cloudburstmc.protocol.bedrock.data.definitions.BlockDefinition;
 import org.cloudburstmc.protocol.bedrock.data.definitions.ItemDefinition;
 import org.cloudburstmc.protocol.bedrock.data.inventory.CreativeItemData;
 import org.cloudburstmc.protocol.bedrock.data.inventory.CreativeItemGroup;
@@ -73,6 +74,11 @@ public class ItemMappings implements DefinitionRegistry<ItemDefinition> {
     List<ItemDefinition> buckets;
     List<ItemDefinition> boats;
     Int2ObjectMap<String> customIdMappings;
+    // the item definition runtime id that is actually for the block
+    // that has the block definition with a 0 runtime id
+    // as of 1.21.110: cyan_terracotta
+    // array since it could be multiple
+    Integer[] zeroBlockDefinitionRuntimeId;
 
     Object2ObjectMap<CustomBlockData, ItemDefinition> customBlockItemDefinitions;
 
@@ -153,7 +159,7 @@ public ItemMapping getMapping(ItemData data) {
             return lightBlock;
         }
 
-        boolean isBlock = data.getBlockDefinition() != null;
+        boolean isBlock = isValidBlockItem(data);
         boolean hasDamage = data.getDamage() != 0;
 
         for (ItemMapping mapping : this.items) {
@@ -180,6 +186,28 @@ public ItemMapping getMapping(ItemData data) {
         return ItemMapping.AIR;
     }
 
+    public boolean isValidBlockItem(ItemData itemData) {
+        BlockDefinition blockDefinition = itemData.getBlockDefinition();
+        if (blockDefinition == null) {
+            return false;
+        }
+
+        if (blockDefinition.getRuntimeId() != 0) {
+            return true;
+        }
+
+        // Bedrock likes sending ""block definitions"" that aren't actually any
+        // Unfortunately, unlike Java, a block definition with runtime id 0 is not air,
+        // but a block. For example, in 1.21.110: cyan terracotta.
+        for (int other : zeroBlockDefinitionRuntimeId) {
+            if (itemData.getDefinition().getRuntimeId() == other) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     @Nullable
     @Override
     public ItemDefinition getDefinition(int bedrockId) {