* <p>For any equivalent elements across all {@code iterables}, it is undefined which element is
   * returned first.
   *
   * @since 11.0
   */
  public static <T extends @Nullable Object> Iterable<T> mergeSorted(
      final Iterable<? extends Iterable<? extends T>> iterables,
      final Comparator<? super T> comparator) {
    checkNotNull(iterables, "iterables");
    checkNotNull(comparator, "comparator");

   * <p>For any equivalent elements across all {@code iterables}, it is undefined which element is
   * returned first.
   *
   * @since 11.0
   */
  public static <T extends @Nullable Object> Iterable<T> mergeSorted(
      final Iterable<? extends Iterable<? extends T>> iterables,
      final Comparator<? super T> comparator) {
    checkNotNull(iterables, "iterables");
    checkNotNull(comparator, "comparator");