jsonrpc2.go
func (r *Request) SetParams(v interface{}) error {
	b, err := json.Marshal(v)
	if err != nil {
		return err
	}
	r.Params = (*json.RawMessage)(&b)
	return nil
}
func (r *Request) SetParams(v interface{}) error {
	b, err := json.Marshal(v)
	if err != nil {
		return err
	}
	r.Params = (*json.RawMessage)(&b)
	return nil
}
// SetParams sets r.Params to the JSON representation of v. If JSON
// marshaling fails, it returns an error.