content.scala

final Subscriber<Integer> subscriber = UntypedActorSubscriber.create(ref);
    final java.util.Iterator<Integer> input = Arrays.asList(1, 2, 3).iterator();
    
    // wrong, because drain == scaladsl => extends scala.Drain, extends scala.Sink
    Source.from(input).connect(new SubscriberDrain<Integer>(subscriber), materializer);

    // wrong, because we only runWith DrainWithKey
    // suggesting to allow runWith(SimpleDrain)?
    Source.from(input).runWith(new SubscriberDrain<Integer>(subscriber), materializer); 

// this is meant to replace produceTo