private @NotNull BulkFileListener getPublisher() {
    BulkFileListener publisher = myPublisher;
    if (publisher == null) {
      // the field cannot be initialized in constructor, to ensure that lazy listeners won't be created too early
      publisher = app.getMessageBus().syncPublisher(VirtualFileManager.VFS_CHANGES);
      myPublisher = publisher;
    }
    return publisher;
  }
private @NotNull BulkFileListener getPublisher()