public void run() {}

    private void setOwner(Thread thread) {
      super.setExclusiveOwnerThread(thread);
    }

    @VisibleForTesting
    @Nullable Thread getOwner() {
      return super.getExclusiveOwnerThread();
    }

    @Override
    public String toString() {
      return task.toString();
    }
  }

  @Override
  public final String toString() {
    Runnable state = get();