it's s bit difficult to know exactly how we would neatly plug in the extension - capabilities. it's certainly possible to do it, but by their very definition there is no defined schema to extension, so the best we could could do would be to provide a hook points to plug in native JSON nodes or auto-json'd parts to the response. Undoubtably because we're generating the JSON from the code, we won't be able to replicate the entirety of the OpenApi spec.