ResourceSubscriber implements FlowableSubscriber<T>, Disposable { public final void add(Disposable resource) { ObjectHelper.requireNonNull(resource, "resource is null"); resources.add(resource); }  final void add(Disposable resource); @Override final void onSubscribe(Subscription s); @Override final void dispose(); @Override final boolean isDisposed();  }
@Test(expected = NullPointerException.class) public void nullResource() { TestResourceSubscriber<Integer> ro = new TestResourceSubscriber<Integer>(); ro.add(null); }