Changes as I was randomly staring at the code

core/src/main/java/org/geysermc/geyser/entity/type/DefaultBlockMinecartEntity.java

@@ -57,7 +57,7 @@ public class DefaultBlockMinecartEntity extends MinecartEntity {
 
     @Override
     public void setCustomBlock(IntEntityMetadata entityMetadata) {
-        customBlock = ((IntEntityMetadata) entityMetadata).getPrimitiveValue();
+        customBlock = entityMetadata.getPrimitiveValue();
 
         if (showCustomBlock) {
             dirtyMetadata.put(EntityData.DISPLAY_ITEM, session.getBlockMappings().getBedrockBlockId(customBlock));

core/src/main/java/org/geysermc/geyser/level/chunk/bitarray/BitArrayVersion.java

@@ -96,7 +96,7 @@ public enum BitArrayVersion {
             // Padded palettes aren't able to use bitwise operations due to their padding.
             return new PaddedBitArray(this, size, words);
         } else if (this == V0) {
-            return new SingletonBitArray();
+            return SingletonBitArray.INSTANCE;
         } else {
             return new Pow2BitArray(this, size, words);
         }

core/src/main/java/org/geysermc/geyser/level/chunk/bitarray/SingletonBitArray.java

@@ -26,13 +26,12 @@
 package org.geysermc.geyser.level.chunk.bitarray;
 
 import io.netty.buffer.ByteBuf;
+import it.unimi.dsi.fastutil.ints.IntArrays;
 
 public class SingletonBitArray implements BitArray {
     public static final SingletonBitArray INSTANCE = new SingletonBitArray();
 
-    private static final int[] EMPTY_ARRAY = new int[0];
+    private SingletonBitArray() {
-
-    public SingletonBitArray() {
     }
 
     @Override
@@ -56,7 +55,7 @@ public class SingletonBitArray implements BitArray {
 
     @Override
     public int[] getWords() {
-        return EMPTY_ARRAY;
+        return IntArrays.EMPTY_ARRAY;
     }
 
     @Override

core/src/main/java/org/geysermc/geyser/registry/AbstractMappedRegistry.java

@@ -29,8 +29,8 @@ import org.geysermc.geyser.registry.loader.RegistryLoader;
 
 import javax.annotation.Nullable;
 import java.util.Map;
-import java.util.Optional;
+import java.util.OptionalInt;
-import java.util.function.Function;
+import java.util.function.ToIntFunction;
 
 /**
  * An abstract registry holding a map of various registrations as defined by {@link M}.
@@ -62,15 +62,14 @@ public abstract class AbstractMappedRegistry<K, V, M extends Map<K, V>> extends
      *
      * @param key the key
      * @param mapper the mapper
-     * @param <U> the type
      * @return the mapped value from the given key if present
      */
-    public <U> Optional<U> map(K key, Function<? super V, ? extends U> mapper) {
+    public OptionalInt map(K key, ToIntFunction<? super V> mapper) {
         V value = this.get(key);
         if (value == null) {
-            return Optional.empty();
+            return OptionalInt.empty();
         } else {
-            return Optional.ofNullable(mapper.apply(value));
+            return OptionalInt.of(mapper.applyAsInt(value));
         }
     }
 

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

@@ -34,6 +34,7 @@ import org.geysermc.geyser.GeyserImpl;
 import org.geysermc.geyser.api.item.custom.CustomItemData;
 import org.geysermc.geyser.api.item.custom.CustomRenderOffsets;
 import org.geysermc.geyser.api.item.custom.NonVanillaCustomItemData;
+import org.geysermc.geyser.api.util.TriState;
 import org.geysermc.geyser.item.GeyserCustomMappingData;
 import org.geysermc.geyser.item.components.ToolBreakSpeedsUtils;
 import org.geysermc.geyser.item.components.WearableSlot;
@@ -171,7 +172,8 @@ public class CustomItemRegistryPopulator {
         itemProperties.putBoolean("allow_off_hand", customItemData.allowOffhand());
         itemProperties.putBoolean("hand_equipped", isTool);
         itemProperties.putInt("max_stack_size", stackSize);
-        if (maxDamage > 0) {
+        // Ignore durability if the item's predicate requires that it be unbreakable
+        if (maxDamage > 0 && customItemData.customItemOptions().unbreakable() != TriState.TRUE) {
             componentBuilder.putCompound("minecraft:durability", NbtMap.builder()
                     .putCompound("damage_chance", NbtMap.builder()
                             .putInt("max", 1)

core/src/main/java/org/geysermc/geyser/session/SessionManager.java

@@ -28,9 +28,9 @@ package org.geysermc.geyser.session;
 import com.google.common.collect.ImmutableList;
 import lombok.AccessLevel;
 import lombok.Getter;
-import lombok.NonNull;
 import org.geysermc.geyser.text.GeyserLocale;
 
+import javax.annotation.Nonnull;
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
 
@@ -69,7 +69,7 @@ public final class SessionManager {
         }
     }
 
-    public GeyserSession sessionByXuid(@NonNull String xuid) {
+    public GeyserSession sessionByXuid(@Nonnull String xuid) {
         Objects.requireNonNull(xuid);
         for (GeyserSession session : sessions.values()) {
             if (session.xuid().equals(xuid)) {

core/src/main/java/org/geysermc/geyser/translator/inventory/item/nbt/CrossbowTranslator.java

@@ -39,8 +39,8 @@ public class CrossbowTranslator extends NbtItemStackTranslator {
 
     @Override
     public void translateToBedrock(GeyserSession session, CompoundTag itemTag, ItemMapping mapping) {
-        if (itemTag.get("ChargedProjectiles") != null) {
         ListTag chargedProjectiles = itemTag.get("ChargedProjectiles");
+        if (chargedProjectiles != null) {
             if (!chargedProjectiles.getValue().isEmpty()) {
                 CompoundTag projectile = (CompoundTag) chargedProjectiles.getValue().get(0);
 

core/src/main/java/org/geysermc/geyser/translator/inventory/item/nbt/LeatherArmorTranslator.java

@@ -32,13 +32,12 @@ import org.geysermc.geyser.session.GeyserSession;
 import org.geysermc.geyser.translator.inventory.item.ItemRemapper;
 import org.geysermc.geyser.translator.inventory.item.NbtItemStackTranslator;
 
-import java.util.Arrays;
 import java.util.List;
 
 @ItemRemapper
 public class LeatherArmorTranslator extends NbtItemStackTranslator {
 
-    private static final List<String> ITEMS = Arrays.asList("minecraft:leather_helmet", "minecraft:leather_chestplate",
+    private static final List<String> ITEMS = List.of("minecraft:leather_helmet", "minecraft:leather_chestplate",
             "minecraft:leather_leggings", "minecraft:leather_boots", "minecraft:leather_horse_armor");
 
     @Override
@@ -47,10 +46,9 @@ public class LeatherArmorTranslator extends NbtItemStackTranslator {
         if (displayTag == null) {
             return;
         }
-        IntTag color = displayTag.get("color");
+        IntTag color = displayTag.remove("color");
         if (color != null) {
             itemTag.put(new IntTag("customColor", color.getValue()));
-            displayTag.remove("color");
         }
     }
 

core/src/main/java/org/geysermc/geyser/translator/level/block/entity/CampfireBlockEntityTranslator.java

@@ -28,6 +28,7 @@ package org.geysermc.geyser.translator.level.block.entity;
 import com.github.steveice10.mc.protocol.data.game.level.block.BlockEntityType;
 import com.github.steveice10.opennbt.tag.builtin.CompoundTag;
 import com.github.steveice10.opennbt.tag.builtin.ListTag;
+import com.github.steveice10.opennbt.tag.builtin.Tag;
 import com.nukkitx.nbt.NbtMap;
 import com.nukkitx.nbt.NbtMapBuilder;
 import org.geysermc.geyser.network.GameProtocol;
@@ -40,7 +41,7 @@ public class CampfireBlockEntityTranslator extends BlockEntityTranslator {
     public void translateTag(NbtMapBuilder builder, CompoundTag tag, int blockState) {
         ListTag items = tag.get("Items");
         int i = 1;
-        for (com.github.steveice10.opennbt.tag.builtin.Tag itemTag : items.getValue()) {
+        for (Tag itemTag : items.getValue()) {
             builder.put("Item" + i, getItem((CompoundTag) itemTag));
             i++;
         }

core/src/test/java/org/geysermc/geyser/translator/inventory/item/CustomItemsTest.java

@@ -72,7 +72,7 @@ public class CustomItemsTest {
         tagToCustomItemWithDamage = new Object2IntOpenHashMap<>();
 
         CompoundTag tag = new CompoundTag("");
-        tag.put(new IntTag("CustomModelData", 6));
+        addCustomModelData(6, tag);
         // Test item with no damage should be treated as unbreakable
         tagToCustomItemWithDamage.put(tag, optionsToId.getInt(a));
 
@@ -121,7 +121,7 @@ public class CustomItemsTest {
         tagToCustomItemWithNoDamage = new Object2IntOpenHashMap<>();
 
         tag = new CompoundTag("");
-        tag.put(new IntTag("CustomModelData", 2));
+        addCustomModelData(2, tag);
         // Damage predicates existing mean an item will never match if the item mapping has no max damage
         tagToCustomItemWithNoDamage.put(tag, -1);