How to set Symfony request while it is wrapped as Behat request object?

Question

I was trying to use Symfony\Component\HttpFoundation\Request->attributes->set('token', 123); when it is wrapped as Behatch\HttpCall\Request, but there is no attributes for the behatch object, there are only setHeader(), setServerParameter(), but these are not what I want, and the getRequest() for the raw Symfony request is protected too, So for this case how to set the attributes of Symfony request?