class CallbackCompletableObserver extends AtomicReference<Disposable> implements CompletableObserver, Disposable, Consumer<Throwable>, LambdaConsumerIntrospection {

    @Override
    public boolean hasCustomOnError() {
        return onError != this;
    }

    public  CallbackCompletableObserver(Action onComplete);
    public  CallbackCompletableObserver(Consumer<? super Throwable> onError, Action onComplete);

}