I'd have to RTFM. But I doubt it. Under certain circumstances, such as after the timeout interval has expired, the container may decide to destroy an HttpSession even though no request/response process is in progress. In fact, timeout pretty much [b]guarantees[/i] no request/response was in progress, since a new request would have reset the timer.
And, of course, if there was no request/response, there's no response object to get hold of.
An IDE is no substitute for an Intelligent Developer.