/**
  * @param Reservation $instance
  * @param ReservationSeries $series
  * @param IReservedItemView $existingItem
  * @param BookableResource[] $keyedResources
  * @return bool
  */
 protected function IsInConflict(Reservation $instance, ReservationSeries $series, IReservedItemView $existingItem, $keyedResources)
 {
     if ($existingItem->GetId() == $instance->ReservationId() || $series->IsMarkedForDelete($existingItem->GetId()) || $series->IsMarkedForUpdate($existingItem->GetId())) {
         return false;
     }
     return parent::IsInConflict($instance, $series, $existingItem, $keyedResources);
 }