Background upload / download using URLSession transport

We are heavily using openapi to generate our REST library.
In this library we do files upload and download.

Everything works pretty well but now we want to allow background requests.
That means we need to use an URLSession with `URLSessionConfiguration.background()`.

I saw we could override the URLSession but the most challenging part is we need a dedicate delegate for each API we have running in the background.

What's the best way to manage that with an openapi generated library?
For now, we are considering doing it manually, so removing this library from our code :'(

The issue does not identify any files, tests, or entry points. Start by locating the URLSession transport implementation and its handling of upload and download delegates, then review how generated APIs configure or override the session. Done would require a documented design and implementation for background requests with separate delegates per API.

Written by the indexing model from the issue text.