please include function jdk_watchService_start.

svoid jdk_watchService_registerRecursivePath(File path, final VF1<File> listener) ctex {
  final Set<File> listeningTo = synchroSet();
  VF1<File> listener2 = voidfunc(File f) {
    // TODO: remove listeners on deleted directory
    bool isDir = f.isDirectory();
    if (isDir && listeningTo.add(f)) pcall-short {
      //print("Watching new subdir: " + f);
      jdk_watchService_registerPath(f, this, jdk_watchService_allEventKinds());
    }
    callF(listener, f);
  };
  jdk_watchService_registerPath(path, listener2, jdk_watchService_allEventKinds());
  for (File subDir : findAllDirs(path))
    jdk_watchService_registerPath(subDir, listener2, jdk_watchService_allEventKinds());
}

Began life as a copy of #1019345