code: public final void validate() throws ValidationException {
  
          /*
           * ; the following are optional, ; but MUST NOT occur more than once (";" cutypeparam) / (";"memberparam) / (";"
           * roleparam) / (";" partstatparam) / (";" rsvpparam) / (";" deltoparam) / (";" delfromparam) / (";"
           * sentbyparam) / (";"cnparam) / (";" dirparam) / (";" languageparam) /
           */
          Arrays.asList(Parameter.CUTYPE, Parameter.MEMBER, Parameter.ROLE, Parameter.PARTSTAT,
                  Parameter.RSVP, Parameter.DELEGATED_TO, Parameter.DELEGATED_FROM, Parameter.SENT_BY, Parameter.CN,
                  Parameter.DIR, Parameter.LANGUAGE).forEach(parameter -> ParameterValidator.getInstance().assertOneOrLess(parameter, getParameters()));
  
          /* scheduleagent and schedulestatus added for CalDAV scheduling
           */
          ParameterValidator.getInstance().assertOneOrLess(Parameter.SCHEDULE_AGENT,
                  getParameters());
          ParameterValidator.getInstance().assertOneOrLess(Parameter.SCHEDULE_STATUS,
                  getParameters());
          /*
           * ; the following is optional, ; and MAY occur more than once (";" xparam)
           */
      }
docs: {@inheritDoc}