private List<StageEntityPK> getAllStageEntityPKForRequest(final Long requestID) {
    Predicate<StageEntityPK> predicate = new Predicate<StageEntityPK>() {
      @Override
      public boolean apply(StageEntityPK stageEntityPK) {
        return stageEntityPK.getRequestId().equals(requestID);
      }
    };
    return  FluentIterable.from(activeStageMap.keySet())
        .filter(predicate)
        .toList();
  }
Filters list of {@link Stage} to list of {@link StageEntityPK}
@param requestID requestId
@return  list of StageEntityPK
ambari-server/src/main/java/org/apache/ambari/server/events/listeners/tasks/TaskStatusListener.java