@RequiresSession
  public AlertDefinitionEntity findByName(long clusterId, String definitionName) {
    TypedQuery<AlertDefinitionEntity> query = entityManagerProvider.get().createNamedQuery(
        "AlertDefinitionEntity.findByName", AlertDefinitionEntity.class);

    query.setParameter("clusterId", clusterId);
    query.setParameter("definitionName", definitionName);

    return daoUtils.selectSingle(query);
  }
Gets an alert definition with the specified name. Alert definition names
are unique within a cluster.

@param clusterId
         the ID of the cluster.
@param definitionName
         the name of the definition (not {@code null}).
@return the alert definition or {@code null} if none exists.
ambari-server/src/main/java/org/apache/ambari/server/orm/dao/AlertDefinitionDAO.java