public class ExampleMod implements ModInitializer {
    [...]
    public static final ScreenHandlerType<BoxScreenHandler> BOX_SCREEN_HANDLER = Registry.register(Registries.SCREEN_HANDLER, Identifier.of("tutorial", "box_block"), new ScreenHandlerType<>(BoxScreenHandler::new, FeatureSet.empty()));
    
    @Override
    public void onInitialize() {
        [...]
    }
}