private void processEvent(@NotNull VFileEvent e, @Nullable VirtualFile file) {
    if (file == null || !shouldProcess(e, file)) return;
    if (isUndoable(e, file)) {
      registerUndoableAction(file);
    }
    else {
      registerNonUndoableAction(file);
    }
  }
private void processEvent(@NotNull VFileEvent e, @Nullable VirtualFile file)