docs: public static Pair<BabySitter, List<String>> blockingFactory(ZooKeeper zk, String dir, Callback cb,
              ExecutorService es)
          throws InterruptedException, ExecutionException
      {
          BabySitter bs = new BabySitter(zk, dir, cb, es);
          List<String> initialChildren;
          try {
              initialChildren = bs.m_eventHandler.call();
          } catch (Exception e) {
              throw new ExecutionException(e);
          }
          return new Pair<BabySitter, List<String>>(bs, initialChildren);
      }