code: public final void validate(final boolean recurse) throws ValidationException {
  
          // From "4.8.3.3 Time Zone Offset From":
          // Conformance: This property MUST be specified in a "VTIMEZONE"
          // calendar component.
          PropertyValidator.getInstance().assertOne(Property.TZOFFSETFROM,
                  getProperties());
  
          // From "4.8.3.4 Time Zone Offset To":
          // Conformance: This property MUST be specified in a "VTIMEZONE"
          // calendar component.
          PropertyValidator.getInstance().assertOne(Property.TZOFFSETTO,
                  getProperties());
  
          /*
           * ; the following are each REQUIRED, ; but MUST NOT occur more than once dtstart / tzoffsetto / tzoffsetfrom /
           */
          PropertyValidator.getInstance().assertOne(Property.DTSTART,
                  getProperties());
  
          /*
           * ; the following are optional, ; and MAY occur more than once comment / rdate / rrule / tzname / x-prop
           */
  
          if (recurse) {
              validateProperties();
          }
      }
docs: {@inheritDoc}