Consider further specializing AugmentableCodecDataObject

public abstract IdenfiableAugmentableCodecDataObject<I extends Identifier<T>, T extends DataObject & Augmentable<T> & Identifiable<I>>
        extends AugmentableCodecDataObject<T> implements Identifiable<I> {

    private static final VarHandle CACHED_KEY;

    static {
        try {
            CACHED_KEY = MethodHandles.lookup().findVarHandle(IdenfiableAugmentableCodecDataObject.class,
                "cachedKey", Identifier.class);
        } catch (ReflectiveOperationException e) {
            throw new ExceptionInInitializerError(e);
        }
    }

    // Used via VarHandle
    @SuppressWarnings("unused")
    private volatile I cachedKey;

    @Override
    public final I key() {
        return (I) codecKey(CACHED_KEY);
    }
}