code: @Override
      public Calendar refresh(VEvent component) {
          Calendar refresh = wrap(Method.REFRESH, component);
          refresh.validate();
          return refresh;
      }
docs: <pre>
  3.2.6.  REFRESH
  
  The "REFRESH" method in a "VEVENT" calendar component is used by
  "Attendees" of an existing event to request an updated description
  from the event "Organizer".  The "REFRESH" method must specify the
  "UID" property of the event to update.  A recurrence instance of an
  event may be requested by specifying the "RECURRENCE-ID" property
  corresponding to the associated event.  The "Organizer" responds with
  the latest description and version of the event.
  </pre>