*
   * <p><b>Java 8+ users:</b> use the method reference {@code Object::toString} instead. In the
   * future, when this class requires Java 8, this method will be deprecated. See {@link Function}
   * for more important information about the Java 8+ transition.
   */
  public static Function<Object, String> toStringFunction() {
    return ToStringFunction.INSTANCE;
  }

  // enum singleton pattern

   *
   * <p><b>Java 8+ users:</b> use the method reference {@code Object::toString} instead. In the
   * future, when this class requires Java 8, this method will be deprecated. See {@link Function}
   * for more important information about the Java 8+ transition.
   */
  public static Function<Object, String> toStringFunction() {
    return ToStringFunction.INSTANCE;
  }

  // enum singleton pattern