@Override
  @Transactional
  public void deleteMultimedia(Multimedia multimedia) {
    Validate.notNull(multimedia, "multimedia can not be null");

    final EntityManager entityManager = this.getEntityManager();

    final MultimediaImpl multimediaImpl =
        entityManager.find(MultimediaImpl.class, multimedia.getMultimediaId());

    final ConferenceUser creator = multimediaImpl.getCreator();
    final ConferenceUserImpl creatorImpl = this.conferenceUserDao.getUser(creator.getUserId());
    creatorImpl.getMultimedias().remove(multimediaImpl);

    entityManager.remove(multimediaImpl);
    // entityManager.remove(creatorImpl);
  }
 private void updateBlackboardMultimedia(
     BlackboardMultimediaResponse multimediaResponse, String filename, MultimediaImpl multimedia) {
   multimedia.setDescription(multimediaResponse.getDescription());
   multimedia.setFilename(filename);
   multimedia.setSize(multimediaResponse.getSize());
 }