@RequiresSession
  public List<ClusterEntity> findAll() {
    TypedQuery<ClusterEntity> query = entityManagerProvider.get().createNamedQuery("allClusters", ClusterEntity.class);
    try {
      return query.getResultList();
    } catch (NoResultException ignored) {
    }
    return null;
  }
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