code: public static boolean isISODateTimeUTC(final String val) throws BadDateException {
      try {
        if (val.length() != 16) {
          return false;
        }
        fromISODateTimeUTC(val);
        return true;
      } catch (Throwable t) {
        return false;
      }
    }
docs: Check Date is "yyyyMMddThhmmddZ"
  
  @param val String to check
  @return boolean
  @throws BadDateException on format error