*
   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
   * use the {@code HashSet} constructor directly, taking advantage of <a
   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
   */
  public static <E extends @Nullable Object> HashSet<E> newHashSet() {
    return new HashSet<>();
  }

  /**