public ClusterEntity merge(ClusterEntity clusterEntity) {
    return merge(clusterEntity, false);
  }
Merge the specified entity into the current persistence context.

@param clusterEntity
         the entity to merge (not {@code null}).
@return the managed entity which was merged (never {@code null}).
ambari-server/src/main/java/org/apache/ambari/server/orm/dao/ClusterDAO.java