@ParametricNullness
  public E getLast() {
    return delegate().getLast();
  }

  @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
  @Override
  public boolean offerFirst(@ParametricNullness E e) {
    return delegate().offerFirst(e);
  }

  @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
  @Override
  public boolean offerLast(@ParametricNullness E e) {
    return delegate().offerLast(e);
  }

  }

  @Override
  public void putLast(E e) throws InterruptedException {
    delegate().putLast(e);
  }

  @Override
  public boolean offerFirst(E e, long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().offerFirst(e, timeout, unit);
  }

  @Override
  public boolean offerLast(E e, long timeout, TimeUnit unit) throws InterruptedException {

    @Override
    public void addLast(E e) {
      assertTrue(Thread.holdsLock(mutex));
      delegate.addLast(e);
    }

    @Override
    public boolean offerFirst(E e) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.offerFirst(e);
    }

    @Override
    public boolean offerLast(E e) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.offerLast(e);
    }

  }

  @Override
  public void putLast(E e) throws InterruptedException {
    delegate().putLast(e);
  }

  @Override
  public boolean offerFirst(E e, long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().offerFirst(e, timeout, unit);
  }

  @Override
  public boolean offerLast(E e, long timeout, TimeUnit unit) throws InterruptedException {

  }

  @Override
  public void putLast(E e) throws InterruptedException {
    delegate().putLast(e);
  }

  @Override
  public boolean offerFirst(E e, long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().offerFirst(e, timeout, unit);
  }

  @Override
  public boolean offerLast(E e, long timeout, TimeUnit unit) throws InterruptedException {

    @Override
    public void addLast(E e) {
      synchronized (mutex) {
        delegate().addLast(e);
      }
    }

    @Override
    public boolean offerFirst(E e) {
      synchronized (mutex) {
        return delegate().offerFirst(e);
      }
    }

    @Override
    public boolean offerLast(E e) {
      synchronized (mutex) {
        return delegate().offerLast(e);
      }

    @Override
    public void addLast(E e) {
      synchronized (mutex) {
        delegate().addLast(e);
      }
    }

    @Override
    public boolean offerFirst(E e) {
      synchronized (mutex) {
        return delegate().offerFirst(e);
      }
    }

    @Override
    public boolean offerLast(E e) {
      synchronized (mutex) {
        return delegate().offerLast(e);
      }