code: public void validate(VAlarm target) throws ValidationException {
          /*
           * ; the following are all REQUIRED,
           * ; but MUST NOT occur more than once action / attach / trigger /
           * ; 'duration' and 'repeat' are both optional,
           * ; and MUST NOT occur more than once each,
           * ; but if one occurs, so MUST the other duration / repeat /
           * ; 'description' is optional,
           * ; and MUST NOT occur more than once description /
           * ; the following is optional, ; and MAY occur more than once x-prop
           */
          PropertyValidator.getInstance().assertOne(ATTACH, target.getProperties());
  
          PropertyValidator.getInstance().assertOneOrLess(DESCRIPTION, target.getProperties());
      }
docs: {@inheritDoc}