public Map<Long, HostRoleCommandStatusSummaryDTO> getStageSummaries(Long requestId) {
    ensureInitialized();
    LogicalRequest request = allRequests.get(requestId);
    return request == null ? Collections.emptyMap() :
        request.getStageSummaries();
  }
Currently we are just returning all stages for all requests
and relying on the StageResourceProvider to convert each to a resource and do a predicate eval on each.
ambari-server/src/main/java/org/apache/ambari/server/topology/TopologyManager.java