code: func (podDisruptionBudgetStrategy) ValidateUpdate(ctx context.Context, obj, old runtime.Object) field.ErrorList {
  	validationErrorList := validation.ValidatePodDisruptionBudget(obj.(*policy.PodDisruptionBudget))
  	updateErrorList := validation.ValidatePodDisruptionBudgetUpdate(obj.(*policy.PodDisruptionBudget), old.(*policy.PodDisruptionBudget))
  	return append(validationErrorList, updateErrorList...)
  }
docs: // ValidateUpdate is the default update validation for an end user.