code: @SuppressWarnings("unused")
    public void addAll(ScalingStats stats)
    {
      synchronized (lock) {
        synchronized (stats.lock) {
          recentEvents.addAll(stats.recentEvents);
        }
      }
    }
docs: This method is unused, but ScalingStats is {@link PublicApi}, so we cannot remove it.
  TODO test this method (it will "count" as usage)