How to monitor link with java watchservice

Question

How to monitor a file updated (file is actual.txt below)? But I just want to monitor the link folder.

ln -s ../actual.txt link

    Path path = Paths.get(".");

    WatchService watchService =  path.getFileSystem().newWatchService();
    path.register(watchService, StandardWatchEventKinds.ENTRY_MODIFY);
    WatchKey watchKey = null;
    while (true) {
        watchKey = watchService.poll(10, TimeUnit.MINUTES);
        if(watchKey != null) {
            watchKey.pollEvents().stream().forEach(event -> System.out.println(event.context()));
        }
        watchKey.reset();
    }

But this code is not work.