Expose what entity types have renderers to the AddLayer event (#562)

src/main/java/net/neoforged/neoforge/client/event/EntityRenderersEvent.java

@@ -25,7 +25,6 @@
 import net.minecraft.client.resources.PlayerSkin;
 import net.minecraft.world.entity.Entity;
 import net.minecraft.world.entity.EntityType;
-import net.minecraft.world.entity.LivingEntity;
 import net.minecraft.world.entity.player.Player;
 import net.minecraft.world.level.block.SkullBlock;
 import net.minecraft.world.level.block.SkullBlock.Type;
@@ -158,6 +157,13 @@ public <R extends EntityRenderer<? extends Player>> R getSkin(PlayerSkin.Model s
             return (R) skinMap.get(skinModel);
         }
 
+        /**
+         * {@return the set of entity types which have a renderer}
+         */
+        public Set<EntityType<?>> getEntityTypes() {
+            return renderers.keySet();
+        }
+
         /**
          * Returns an entity renderer for the given entity type. Note that the returned renderer may not be a
          * {@link LivingEntityRenderer}.
@@ -169,7 +175,7 @@ public <R extends EntityRenderer<? extends Player>> R getSkin(PlayerSkin.Model s
          */
         @Nullable
         @SuppressWarnings("unchecked")
-        public <T extends LivingEntity, R extends EntityRenderer<T>> R getRenderer(EntityType<? extends T> entityType) {
+        public <T extends Entity, R extends EntityRenderer<T>> R getRenderer(EntityType<? extends T> entityType) {
             return (R) renderers.get(entityType);
         }