code: public static String escapeRegExp(String string)
    {
      if(string == null) {
        return null;
      }
      return string.replaceAll(REGEXP_PATTERN, REPLACE_ARG_REX);
    }
docs: Escape string for regular expression reserved characters. Return null if string argument is null and empty if
  empty.
  
  @param string regular expression to escape.
  @return newly created, escaped string.