server_handlers.go
func postCallback(opts *ServerOptions) Handler {
	return func(_ io.Writer, r io.Reader, _ httprouter.Params) error {
		req := &CallbackRequest{}
		err := json.NewDecoder(r).Decode(req)
		if err != nil {
			return err
		}
		return opts.Controller.Callback(req)
	}
}
func postCallback(opts *ServerOptions) Handler {
	return func(_ io.Writer, r io.Reader, _ httprouter.Params) error {
		req := &CallbackRequest{}
		err := json.NewDecoder(r).Decode(req)
		if err != nil {
			return err
		}
		return opts.Controller.Callback(req)
	}
}
// opengdpr_callbacks