void unregisterForUpdates(FinishableStateUpdateHandler handler) {
      lock.lock();
      try {
        EntityInfo info = trackedEntities.remove(handler);
        Preconditions.checkState(info != null,
            "Cannot invoke unregister on an entity which has not been registered");
        for (String source : info.getSources()) {
          sourceToEntity.remove(source, info);
        }
      } finally {
        lock.unlock();
      }
    }
@param handler
@param sources
@param fragmentInfo
@param lastFinishableState
@return true if the current state is the same as the lastFinishableState. false if the state has already changed.
llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/QueryInfo.java