}
  }

  /**
   * Implementation of {@link Stream#flatMap} with an object spliterator output type.
   *
   * <p>To avoid having this type, we could use {@code FlatMapSpliterator} directly. The main
   * advantages to having the type are the ability to use its constructor reference below and the
   * parallelism with the primitive version. In short, it makes its caller ({@code flatMap})
   * simpler.
   *