function GetEventRecurChanges($Event, $RSet)
 {
     if (array_key_exists($Event->Source->GetSourceId(), $this->mSources)) {
         return $this->mSources[$Event->Source->GetSourceId()]->GetEventRecurChanges($Event, $RSet);
     } else {
         return parent::GetEventRecurChanges($Event, $RSet);
     }
 }