Is your feature request related to a problem? Please describe.

Yes, I would need to support "application/octet-stream" in the Swift generator.

Describe the solution you'd like

1. In URLSessionRequestBuilder.execute(), check if contentType.hasPrefix("application/octet-stream") and initialize OctetStreamEncoding()
2. Create a new OctetStreamEncoding class
3. Duplicate FormURLEncoding content and replace "application/x-www-form-urlencoded" by "application/octet-stream" to OctetStreamEncoding

Describe alternatives you've considered

Override URLSessionRequestBuilder.execute() but it will duplicate too many lines

Additional context

I need to be able to upload a file into a server accepting only content-type: "application/octet-stream"