static class OwnerReentrantLock extends ReentrantLock {
        @Override
        public Thread getOwner() {
            return super.getOwner();
        }
    }

    static class OwnerReentrantReadWriteLock extends ReentrantReadWriteLock {
        @Override
        public Thread getOwner() {
            return super.getOwner();
        }
    }

    private static void warn(String msg) {

    private Blocker(InterruptibleTask<?> task) {
      this.task = task;
    }

    @Override
    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();