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: admissionregistration.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 specs

import (
	"encoding/json"
	"fmt"

	"github.com/juju/errors"
	admissionregistrationv1 "k8s.io/api/admissionregistration/v1"
	admissionregistrationv1beta1 "k8s.io/api/admissionregistration/v1beta1"
)

const (
	// K8sWebhookV1Beta1 defines the v1beta1 API version for webhook resources.
	K8sWebhookV1Beta1 APIVer
    
func (w K8sMutatingWebhook) Validate() error {
	if err := w.Meta.Validate(); err != nil {
		return errors.Trace(err)
	}
	if len(w.Webhooks) == 0 {
		return errors.NotValidf("empty webhooks %q", w.Name)
	}
	ver := w.APIVersion()
	for _, v := range w.Webhooks[1:] {
		if v.Version != ver {
			return errors.NewNotValid(nil, fmt.Sprintf("more than one version of webhooks in same spec, found %q and %q", ver, v.Version))
		}
	}
	return nil
}