@TestOnly
  public static void checkCleared(@Nullable Editor editor) {
    if (editor == null) {
      return;
    }
    try {
      StartMarkAction markAction = editor.getUserData(START_MARK_ACTION_KEY);
      assert markAction == null : markAction.myDocument;
    }
    finally {
      editor.putUserData(START_MARK_ACTION_KEY, null);
    }
  }
@TestOnly
  public static void checkCleared(@Nullable Editor editor)