code: public static int requireIntParameter (
          HttpServletRequest req, String name, String invalidDataMessage)
          throws DataValidationException
      {
          return parseIntParameter(getParameter(req, name, false), invalidDataMessage);
      }
docs: Fetches the supplied parameter from the request and converts it to an integer. If the
  parameter does not exist or is not a well-formed integer, a data validation exception is
  thrown with the supplied message.