validateRegistrationData example

$data->set('billingAddress', new RequestDataBag());
        }

        if ($data->has('accountType') && empty($data->get('accountType'))) {
            $data->remove('accountType');
        }

        if (!$data->get('salutationId')) {
            $data->set('salutationId', $this->getDefaultSalutationId($context));
        }

        $this->validateRegistrationData($data, $isGuest, $context, $additionalValidationDefinitions, $validateStorefrontUrl);

        $customer = $this->mapCustomerData($data, $isGuest, $context);

        /** @var DataBag $billing */
        $billing = $data->get('billingAddress');

        if ($data->has('title')) {
            $billing->set('title', $data->get('title'));
        }

        $billingAddress = $this->mapBillingAddress($billing, $context->getContext());