src/game/java/com/mojang/blaze3d/resource/ResourceHandle.java

package com.mojang.blaze3d.resource;

import net.minecraftforge.api.distmarker.Dist;
import net.minecraftforge.api.distmarker.OnlyIn;

@OnlyIn(Dist.CLIENT)
public interface ResourceHandle<T> {
    ResourceHandle<?> INVALID_HANDLE = () -> {
        throw new IllegalStateException("Cannot dereference handle with no underlying resource");
    };

    static <T> ResourceHandle<T> invalid() {
        return (ResourceHandle<T>)INVALID_HANDLE;
    }

    T get();
}