[1.18.x] Add Forge "bosses" tag (#9513)

src/generated/resources/data/forge/tags/entity_types/bosses.json

@@ -0,0 +1,7 @@
+{
+  "replace": false,
+  "values": [
+    "minecraft:ender_dragon",
+    "minecraft:wither"
+  ]
+}

src/main/java/net/minecraftforge/common/ForgeMod.java

@@ -24,6 +24,7 @@ import net.minecraftforge.common.crafting.DifferenceIngredient;
 import net.minecraftforge.common.crafting.IntersectionIngredient;
 import net.minecraftforge.common.data.ExistingFileHelper;
 import net.minecraftforge.common.data.ForgeBiomeTagsProvider;
+import net.minecraftforge.common.data.ForgeEntityTypeTagsProvider;
 import net.minecraftforge.common.data.ForgeFluidTagsProvider;
 import net.minecraftforge.common.extensions.IForgeEntity;
 import net.minecraftforge.common.extensions.IForgePlayer;
@@ -235,6 +236,7 @@ public class ForgeMod
             gen.addProvider(new ForgeRecipeProvider(gen));
             gen.addProvider(new ForgeLootTableProvider(gen));
             gen.addProvider(new ForgeBiomeTagsProvider(gen, existingFileHelper));
+            gen.addProvider(new ForgeEntityTypeTagsProvider(gen, existingFileHelper));
         }
     }
 

src/main/java/net/minecraftforge/common/Tags.java

@@ -12,6 +12,7 @@ import net.minecraft.tags.BlockTags;
 import net.minecraft.tags.FluidTags;
 import net.minecraft.tags.ItemTags;
 import net.minecraft.tags.TagKey;
+import net.minecraft.world.entity.EntityType;
 import net.minecraft.world.item.DyeColor;
 import net.minecraft.world.item.Item;
 import net.minecraft.world.level.biome.Biome;
@@ -31,6 +32,7 @@ public class Tags
         Items.init();
         Fluids.init();
         Biomes.init();
+        EntityTypes.init();
     }
 
     public static class Blocks
@@ -483,4 +485,16 @@ public class Tags
             return TagKey.create(Registry.BIOME_REGISTRY, new ResourceLocation("forge", name));
         }
     }
+
+    public static class EntityTypes
+    {
+        private static void init() {}
+
+        public static final TagKey<EntityType<?>> BOSSES = tag("bosses");
+
+        private static TagKey<EntityType<?>> tag(String name)
+        {
+            return TagKey.create(Registry.ENTITY_TYPE_REGISTRY, new ResourceLocation("forge", name));
+        }
+    }
 }

src/main/java/net/minecraftforge/common/data/ForgeEntityTypeTagsProvider.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.common.data;
+
+import net.minecraft.data.DataGenerator;
+import net.minecraft.data.tags.EntityTypeTagsProvider;
+import net.minecraft.world.entity.EntityType;
+import net.minecraftforge.common.Tags;
+
+public final class ForgeEntityTypeTagsProvider extends EntityTypeTagsProvider
+{
+    public ForgeEntityTypeTagsProvider(DataGenerator generator, ExistingFileHelper existingFileHelper)
+    {
+        super(generator, "forge", existingFileHelper);
+    }
+
+    @Override
+    protected void addTags()
+    {
+        tag(Tags.EntityTypes.BOSSES).add(EntityType.ENDER_DRAGON, EntityType.WITHER);
+    }
+
+    @Override
+    public String getName()
+    {
+        return "Forge EntityType Tags";
+    }
+}