@RequiresSession
  public ClusterConfigEntity findConfig(Long configEntityPK) {
    return entityManagerProvider.get().find(ClusterConfigEntity.class,
      configEntityPK);
  }
Looks for Cluster by ID
@param id ID of Cluster
@return Found entity or NULL
ambari-server/src/main/java/org/apache/ambari/server/orm/dao/ClusterDAO.java