code: func (namespaceStrategy) ValidateUpdate(ctx context.Context, obj, old runtime.Object) field.ErrorList {
  	errorList := validation.ValidateNamespace(obj.(*api.Namespace))
  	return append(errorList, validation.ValidateNamespaceUpdate(obj.(*api.Namespace), old.(*api.Namespace))...)
  }
docs: // ValidateUpdate is the default update validation for an end user.