code: public static SubscriberState empty() {
          val map = new ConcurrentHashMap<String, Number>();
          return SubscriberState.builder().serverState("empty").streamId(-1)
                          .parameterUpdaterStatus(map).totalUpdates(-1).isMaster(false).build();
      }
docs: Returns an empty subscriber state
  with -1 as total updates, master as false
  and server state as empty
  @return an empty subscriber state