@TestOnly
  public void startup(@Nullable Consumer<? super String> notifier) throws Exception {
    myTestNotifier = notifier;
    myFileWatcherExecutor.submit(() -> {
      for (PluggableFileWatcher watcher : PluggableFileWatcher.EP_NAME.getIterable()) {
        if (watcher != null) {
          watcher.startup();
        }
      }
      return null;
    }).get();
  }
@TestOnly
  public void startup(@Nullable Consumer<? super String> notifier)