/** @see org.kuali.rice.ken.service.impl.ConcurrentJob#takeAvailableWorkItems() */
 @Override
 protected Collection<NotificationMessageDelivery> takeAvailableWorkItems() {
   return messageDeliveryService.takeMessageDeliveriesForAutoRemoval();
 }
 /** @see org.kuali.rice.ken.service.impl.ConcurrentJob#unlockWorkItem(java.lang.Object) */
 @Override
 protected void unlockWorkItem(NotificationMessageDelivery delivery) {
   messageDeliveryService.unlockMessageDelivery(delivery);
 }