* too.
   *
   * @since 17.0
   */
  public static <T extends @Nullable Object> ImmutableList<ListenableFuture<T>> inCompletionOrder(
      Iterable<? extends ListenableFuture<? extends T>> futures) {
    ListenableFuture<? extends T>[] copy = gwtCompatibleToArray(futures);
    InCompletionOrderState<T> state = new InCompletionOrderState<>(copy);