code: func (strategy) ValidateUpdate(ctx context.Context, obj, old runtime.Object) field.ErrorList {
  	newObj := obj.(*rbac.ClusterRoleBinding)
  	errorList := validation.ValidateClusterRoleBinding(newObj)
  	return append(errorList, validation.ValidateClusterRoleBindingUpdate(newObj, old.(*rbac.ClusterRoleBinding))...)
  }
docs: // ValidateUpdate is the default update validation for an end user.