public Collection<HostRoleCommand> getTasks(Collection<Long> requestIds) {
    ensureInitialized();
    Collection<HostRoleCommand> tasks = new ArrayList<>();
    for (long id : requestIds) {
      tasks.addAll(getTasks(id));
    }

    return tasks;
  }
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