public AlertDefinition getAggregateDefinition(long clusterId, String name) {
    Long id = Long.valueOf(clusterId);
    if (!m_aggregateMap.containsKey(id)) {
      return null;
    }

    if (!m_aggregateMap.get(id).containsKey(name)) {
      return null;
    }

    return m_aggregateMap.get(id).get(name);
  }
Gets an aggregate definition based on a given alert definition name.

@param clusterId
         the ID of the cluster that the definition is bound to.
@param name
         the unique name of the definition.
@return the aggregate definition, or {@code null} if none.
ambari-server/src/main/java/org/apache/ambari/server/state/alert/AggregateDefinitionMapping.java