docs: public Map<String, Object> getDebugInfo()
    {
      Preconditions.checkArgument(lifecycleLock.awaitStarted(1, TimeUnit.MILLISECONDS));
  
      Map<String, Object> result = new HashMap<>(workers.size());
      for (Map.Entry<String, WorkerHolder> e : workers.entrySet()) {
        WorkerHolder serverHolder = e.getValue();
        result.put(
            e.getKey(),
            serverHolder.getUnderlyingSyncer().getDebugInfo()
        );
      }
      return result;
    }