There isn't support for multipart/form-data right now, but you can use use the [Body] tag to stream the binary directly.

See https://github.com/D-Haven/DHaven.Faux/blob/develop/DHaven.Faux.Test/ParameterTypes/IBlobStore.cs for an example. Specifically:

    [HttpPost("/")]
    [return: ResponseHeader("ETag")]
    Task<string> Upload([Body(Format = Format.Raw)] Stream content, [RequestHeader("Content-Type")] string mimeType,
        [RequestHeader("Content-Length")] long length, [RequestHeader("Content-Disposition")] string disposition);

Ok, got it. Thanks for your support.

This link is for my reference.... when I eventually get multipart:

https://stackoverflow.com/questions/16416601/c-sharp-httpclient-4-5-multipart-form-data-upload

I will likely have to include some type of support for the HttpPost header to mark the method as multipart/form-data encoding. It will have an impact on how I generate the code that prepares the request object.