}

  interface Cancellable {
    void cancel(boolean mayInterruptIfRunning);

    boolean isCancelled();
  }

  private static final class FutureAsCancellable implements Cancellable {
    private final Future<?> delegate;

    FutureAsCancellable(Future<?> delegate) {
      this.delegate = delegate;
    }

    @Override
    @SuppressWarnings("Interruption") // We are propagating an interrupt from a caller.