Hey guys, first of all amazing library. We use your library at work to generate GraphQL types for our internal Swagger APIs. We have pretty huge schemas at our company and some of them rely on the usage of oneOf for polymorphism in responses.

I created a pull request with my current changes and as you can see in #330 it now correctly generates unions for oneOf responses. It took a lot of effort on my behalf to figure out where to apply even these small changes and now I'm kinda stuck. My changes are probably a bit naive, so I'm reaching out and asking for your help and feedback to get this change into your library. :)

I already tested this change against our internal .yaml which is about 2500 lines and everything was generated without a problem. So I'm pretty confident it's "ok". Still...

What am I probably missing, that could break this? What tests do I have to add if any? I'm really looking forward to your response, because we are in need of that feature to continue using your library.

Thanks in advance and best regards
Flo