if ( log.isDebugEnabled() ) {
                    log.debug("Have intermediate reply " + response);
                }

                if ( first ) {
                    int credit = resp.getCredit();
                    if ( log.isDebugEnabled() ) {
                        log.debug("Credit from intermediate " + credit);
                    }
                    this.credits.release(credit);

   *   <li>{@link Cancellation} terminal state, {@code cancel} was called.
   *   <li>{@link Failure} terminal state, {@code setException} was called.
   *   <li>{@link SetFuture} intermediate state, {@code setFuture} was called.
   *   <li>{@link #NULL} terminal state, {@code set(null)} was called.
   *   <li>Any other non-null value, terminal state, {@code set} was called with a non-null
   *       argument.

   * array whose contents are initially non-null. The {@code @Nullable} annotation indicates that
   * this method will write nulls into the array during iteration.
   *
   * <p>This is mainly just to avoid the intermediate ArrayDeque in ConsumingQueueIterator.
   */
  private static <I extends Iterator<?>> Iterator<I> consumingForArray(@Nullable I... elements) {
    return new UnmodifiableIterator<I>() {
      int index = 0;

   * array whose contents are initially non-null. The {@code @Nullable} annotation indicates that
   * this method will write nulls into the array during iteration.
   *
   * <p>This is mainly just to avoid the intermediate ArrayDeque in ConsumingQueueIterator.
   */
  private static <I extends Iterator<?>> Iterator<I> consumingForArray(@Nullable I... elements) {
    return new UnmodifiableIterator<I>() {
      int index = 0;