Decline method
Implementation
Future<CalendarActionResults> Decline(bool sendResponse) {
  throw NotImplementedException("Decline");
//            DeclineMeetingInvitationMessage decline = this.CreateDeclineMessage();
//
//            if (sendResponse)
//            {
//                return decline.SendAndSaveCopy();
//            }
//            else
//            {
//                return decline.Save();
//            }
}