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