You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: ingress.go
    path of file: ./repos/juju/caas/kubernetes/provider/specs
    
    the code of the file until where you have to start completion: // Copyright 2021 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.

package spe
    
func (ing K8sIngressSpec) MarshalJSON() ([]byte, error) {
	switch ing.Version {
	case K8sIngressV1Beta1:
		return json.Marshal(ing.SpecV1Beta1)
	case K8sIngressV1:
		return json.Marshal(ing.SpecV1)
	default:
		return []byte{}, errors.NotSupportedf("ingress version %q", ing.Version)
	}
}