*
   * <p>The returned comparator is serializable.
   *
   * <p><b>Java 8+ users:</b> Use the lambda expression {@code (a, b) -> 0} instead (in certain
   * cases you may need to cast that to {@code Comparator<YourType>}).
   *
   * @since 13.0
   */
  public static Ordering<@Nullable Object> allEqual() {
    return AllEqualOrdering.INSTANCE;
  }

  /**