### Question:
MaybeCallbackObserver extends AtomicReference<Disposable> implements MaybeObserver<T>, Disposable, LambdaConsumerIntrospection { @Override public boolean hasCustomOnError() { return onError != Functions.ON_ERROR_MISSING; } MaybeCallbackObserver(Consumer<? super T> onSuccess, Consumer<? super Throwable> onError,
            Action onComplete); @Override void dispose(); @Override boolean isDisposed(); @Override void onSubscribe(Disposable d); @Override void onSuccess(T value); @Override void onError(Throwable e); @Override void onComplete(); @Override boolean hasCustomOnError();  }### Answer:
@Test public void onErrorMissingShouldReportNoCustomOnError() { MaybeCallbackObserver<Integer> o = new MaybeCallbackObserver<Integer>(Functions.<Integer>emptyConsumer(), Functions.ON_ERROR_MISSING, Functions.EMPTY_ACTION); assertFalse(o.hasCustomOnError()); }
@Test public void customOnErrorShouldReportCustomOnError() { MaybeCallbackObserver<Integer> o = new MaybeCallbackObserver<Integer>(Functions.<Integer>emptyConsumer(), Functions.<Throwable>emptyConsumer(), Functions.EMPTY_ACTION); assertTrue(o.hasCustomOnError()); }