docs: public void exists(final String path, Watcher watcher, StatCallback cb,
              Object ctx) {
          verbotenThreadCheck();
          final String clientPath = path;
          PathUtils.validatePath(clientPath);
  
          // the watch contains the un-chroot path
          WatchRegistration wcb = null;
          if (watcher != null) {
              wcb = new ExistsWatchRegistration(watcher, clientPath);
          }
  
          final String serverPath = prependChroot(clientPath);
  
          RequestHeader h = new RequestHeader();
          h.setType(ZooDefs.OpCode.exists);
          ExistsRequest request = new ExistsRequest();
          request.setPath(serverPath);
          request.setWatch(watcher != null);
          SetDataResponse response = new SetDataResponse();
          cnxn.queuePacket(h, new ReplyHeader(), request, response, cb,
                  clientPath, serverPath, ctx, wcb);
      }