code: func (statefulSetStrategy) ValidateUpdate(ctx context.Context, obj, old runtime.Object) field.ErrorList {
  	newStatefulSet := obj.(*apps.StatefulSet)
  	oldStatefulSet := old.(*apps.StatefulSet)
  	validationErrorList := validation.ValidateStatefulSet(newStatefulSet)
  	updateErrorList := validation.ValidateStatefulSetUpdate(newStatefulSet, oldStatefulSet)
  	updateErrorList = append(updateErrorList, corevalidation.ValidateConditionalPodTemplate(&newStatefulSet.Spec.Template, &oldStatefulSet.Spec.Template, field.NewPath("spec.template"))...)
  	return append(validationErrorList, updateErrorList...)
  }
docs: // ValidateUpdate is the default update validation for an end user.