code: @CheckReturnValue
      @BackpressureSupport(BackpressureKind.FULL)
      @SchedulerSupport(SchedulerSupport.NONE)
      public final Flowable<T> repeatWhen(final Function<? super Flowable<Object>, ? extends Publisher<?>> handler) {
          ObjectHelper.requireNonNull(handler, "handler is null");
          return RxJavaPlugins.onAssembly(new FlowableRepeatWhen<T>(this, handler));
      }
docs: Returns a Flowable that emits the same values as the source Publisher with the exception of an
  {@code onComplete}. An {@code onComplete} notification from the source will result in the emission of
  a {@code void} item to the Publisher provided as an argument to the {@code notificationHandler}
  function. If that Publisher calls {@code onComplete} or {@code onError} then {@code repeatWhen} will
  call {@code onComplete} or {@code onError} on the child subscription. Otherwise, this Publisher will
  resubscribe to the source Publisher.
  <p>
  <img width="640" height="430" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/repeatWhen.f.png" alt="">
  <dl>
  <dt><b>Backpressure:</b></dt>
  <dd>The operator honors downstream backpressure and expects the source {@code Publisher} to honor backpressure as well.
  If this expectation is violated, the operator <em>may</em> throw an {@code IllegalStateException}.</dd>
  <dt><b>Scheduler:</b></dt>
  <dd>{@code repeatWhen} does not operate by default on a particular {@link Scheduler}.</dd>
  </dl>
  
  @param handler
  receives a Publisher of notifications with which a user can complete or error, aborting the repeat.
  @return the source Publisher modified with repeat logic
  @see <a href="http://reactivex.io/documentation/operators/repeat.html">ReactiveX operators documentation: Repeat</a>