[cronet_http] - No way to retrieve information about the negotiated protocol

[giannissterg]

Using cronet_http for a research application, I have encountered a lacking feature. I would like to know the protocol I have agreed upon with the server I am communicating with. Specifically, I want to know whether the server has responded with an http/2 or an http/3 response.

From the native side, I can access this information, through UrlResponseInfo.getNegotiatedProtocol().

I should clarify that there doesn't seem to exist an appropriate field to the StreamedResponse class, thereby lack of access to this information is to be expected. Maybe there should also be a feature request for the negotiated protocol to the StreamedResponse class.

I have locally implemented the change, by adding this information to the response headers.