* 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;

      @Override

   * 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;

      @Override