public function getByOccurrenceID($occurrenceID, $retrieveVersion = EventService::EVENT_VERSION_APPROVED)
    {
        if ($retrieveVersion == EventService::EVENT_VERSION_RECENT) {
            $query = $this->entityManager->createQuery('select vo from calendar:CalendarEventVersionOccurrence vo JOIN
    vo.version v JOIN vo.occurrence o where o.occurrenceID = :occurrenceID order by v.evDateAdded DESC');
        } else {
            $query = $this->entityManager->createQuery('select vo from calendar:CalendarEventVersionOccurrence vo JOIN
    vo.version v JOIN vo.occurrence o where o.occurrenceID = :occurrenceID and v.evIsApproved = 1');
        }
        $query->setMaxResults(1);
        $query->setParameter('occurrenceID', $occurrenceID);
        $object = $query->getOneOrNullResult();
        return $object;
    }