Before you ask, I don't control the response, so I can't do something more sane :) And it's on Android, so memory can be quite restrictive, and GC hurts a lot with so much allocation.
I don't see an easy way to plug those requirements into this library. Superficially it seems I can modify/add something inherited from BaseRequest and add my own HttpClientHelper.requestAsync-style method to do this, but it's yet another library that doesn't quite allow this kind of thing natively.
But by the time I've understood and made those changes, I might as well just do it all by hand in that particular request. This is especially true since my code has to be read and understood by others I work with, and it makes updating the Unirest library a much more error-prone event that might leave people in the lurch since they didn't write the extension. There's no real happy solution.
Not that I really think it should easily handle my case - it looks really nice to use, and it's probably not worth it to you / most people, and my case is weird and might ruin everything to properly support. But it's a minor thing that annoys me a bit and makes me want to make my own (minor annoyances are a major motivator for my personal projects). Before I can make anything decent though I need to see a few more ways to do things, try a few crazy architectures, etc. This has helped remind me what it can look like at least, and the code looks surprisingly clean underneath. Definitely a worthwhile read :)