@Override
  public void start(ScheduledExecutorService timer, int interval) {
    timer.scheduleWithFixedDelay(new ThreadIdToSequenceIdExpiryTask(), interval, interval,
        TimeUnit.MILLISECONDS);
  }
test hook - access to this map should be synchronized on the map to avoid concurrent
modification exceptions
geode-core/src/main/java/org/apache/geode/cache/client/internal/QueueStateImpl.java