Not possible to access the message headers via a 'context' on a response

[ramonsmits]

When using callbacks it is not possible to access header data via the context on a response. Meaning that if an endpoint does something like the following the receiver of the response is unable to process this:

Client

var response = await endpoint.Request<MyResponse>(new MyRequest())
// No access to header data

Server

Task Handle(MyRequest request, IMessageHandlerContext context)
{
    var replyOptions = new ReplyOptions();
    var replyOptions.SetHeader("MyHeaderKey", "All your base are belong to us!");
    return context.Reply(new MyResponse(), replyOptions);
}

For this to work we would require an overload like any of the following or even a different signature:

var responseEnvelope = await bus.RequestWithHeaders<MyResponse>(new MyRequest(), options)
var headerValue = responseEnvelope.Headers["MyHeaderKey"]
var message = responseEnvelope.Message;

-or-

await bus.Request<MyResponse>(new MyRequest(), options,  Func<MyResponse,CallbackResponseContext>)

[bording]

@ramonsmits What use case do you see for doing this that couldn't just be handled by adding the value to the message directly?