code: public static <T> Future<T> fromPublisher(final Publisher<T> pub, final Executor ex) {
          final ValueSubscriber<T> sub = ValueSubscriber.subscriber();
          pub.subscribe(sub);
          return sub.toFutureAsync(ex);
      }
docs: Construct a Future asynchronously that contains a single value extracted from the supplied reactive-streams Publisher
  
  
  <pre>
  {@code
  ReactiveSeq<Integer> stream =  ReactiveSeq.of(1,2,3);
  
  Future<Integer> future = Future.fromPublisher(stream,ex);
  
  Future[1]
  
  }
  </pre>
  
  
  @param pub Publisher to extract value from
  @param ex Executor to extract value on
  @return Future populated asyncrhonously from Publisher