code: public static OptionalLong createLong(final String str) {
          if (N.isNullOrEmpty(str)) {
              return OptionalLong.empty();
          }
  
          try {
              return OptionalLong.of(Long.decode(str));
          } catch (NumberFormatException e) {
              return OptionalLong.empty();
          }
      }
docs: <p>
  Convert a <code>String</code> to a <code>Long</code>; since 3.1 it
  handles hex (0Xhhhh) and octal (0ddd) notations. N.B. a leading zero
  means octal; spaces are not trimmed.
  </p>
  
  <p>
  Returns an empty {@code OptionalLong} if the string is {@code null} or can't be parsed as {@code Long}.
  </p>
  
  @param str a <code>String</code> to convert, may be null
  @return