@Override
  public Map<String, Object> getSessionAttributes() {
    Map<String, Object>  attributes =
        (Map<String, Object>) getSessionManager().getAttribute(getClusterSessionAttributeName());

    return attributes == null ? Collections.emptyMap() : attributes;
  }
@param serviceName name of the service
@param componentName name of the component
@return the set of hosts for the provided service and component
ambari-server/src/main/java/org/apache/ambari/server/state/cluster/ClusterImpl.java