code: func (networkPolicyStrategy) ValidateUpdate(ctx context.Context, obj, old runtime.Object) field.ErrorList {
  	validationErrorList := validation.ValidateNetworkPolicy(obj.(*networking.NetworkPolicy))
  	updateErrorList := validation.ValidateNetworkPolicyUpdate(obj.(*networking.NetworkPolicy), old.(*networking.NetworkPolicy))
  	updateErrorList = append(updateErrorList, validation.ValidateConditionalNetworkPolicy(obj.(*networking.NetworkPolicy), old.(*networking.NetworkPolicy))...)
  	return append(validationErrorList, updateErrorList...)
  }
docs: // ValidateUpdate is the default update validation for an end user.