docs: public static boolean setOnce(AtomicReference<Disposable> upstream, Disposable next, Class<?> observer) {
      AutoDisposeUtil.checkNotNull(next, "next is null");
      if (!upstream.compareAndSet(null, next)) {
        next.dispose();
        if (upstream.get() != AutoDisposableHelper.DISPOSED) {
          reportDoubleSubscription(observer);
        }
        return false;
      }
      return true;
    }