@Transactional
  public AlertTargetEntity merge(AlertTargetEntity alertTarget) {
    return entityManagerProvider.get().merge(alertTarget);
  }
Merge the speicified alert target with the existing target in the database.

@param alertTarget
         the target to merge (not {@code null}).
@return the updated target with merged content (never {@code null}).
ambari-server/src/main/java/org/apache/ambari/server/orm/dao/AlertDispatchDAO.java