code: public final void validate() throws ValidationException {
  
          /*
           * ; the following are optional, ; but MUST NOT occur more than once (";" cnparam) / (";" dirparam) / (";"
           * sentbyparam) / (";" languageparam) /
           */
          Arrays.asList(Parameter.CN, Parameter.DIR, Parameter.SENT_BY,
                  Parameter.LANGUAGE).forEach(parameter -> ParameterValidator.getInstance().assertOneOrLess(parameter, getParameters()));
  
          /* schedulestatus added for CalDAV scheduling
           */
          ParameterValidator.getInstance().assertOneOrLess(Parameter.SCHEDULE_STATUS,
                  getParameters());
  
          /*
           * ; the following is optional, ; and MAY occur more than once (";" xparam)
           */
      }
docs: {@inheritDoc}