code: function updateCalendarObject(calendarObject, options) {
    options.contentType = options.contentType || "text/calendar; charset=utf-8";
  
    return webdav.updateObject(calendarObject.url, calendarObject.calendarData, calendarObject.etag, options);
  }
docs: @param {dav.CalendarObject} calendarObject updated calendar object.
  @return {Promise} promise will resolve when the calendar has been updated.
  
  Options:
  
  (dav.Sandbox) sandbox - optional request sandbox.
  (dav.Transport) xhr - request sender.