docs: public static boolean setOnce(AtomicReference<Subscription> upstream, Subscription next, Class<?> subscriber) {
      AutoDisposeUtil.checkNotNull(next, "next is null");
      if (!upstream.compareAndSet(null, next)) {
        next.cancel();
        if (upstream.get() != AutoSubscriptionHelper.CANCELLED) {
          reportDoubleSubscription(subscriber);
        }
        return false;
      }
      return true;
    }