abstract class ForwardingLock implements Lock {
  abstract Lock delegate();

  @Override
  public void lock() {
    delegate().lock();
  }

  @Override
  public void lockInterruptibly() throws InterruptedException {
    delegate().lockInterruptibly();
  }

  @Override
  public boolean tryLock() {
    return delegate().tryLock();
  }

  @Override

      try {
        super.lock();
      } finally {
        lockStateChanged(this);
      }
    }

    @Override
    public void lockInterruptibly() throws InterruptedException {
      aboutToAcquire(this);
      try {
        super.lockInterruptibly();
      } finally {
        lockStateChanged(this);
      }
    }

    @Override
    public boolean tryLock() {
      aboutToAcquire(this);