Persist a TYPO3.Form to my own domain model by extending RedirectFinisher

AccountController.php

/**
     * Shows a form for creating a new account object
     *
     * @return void
     */
    public function newAction() {
    }

    /**
     * Adds the given new account object to the account repository
     *
     * @param string $username
     * @param string $firstname
     * @param string $lastname
     * @param string $password1
     *
     * @return void
     */
    public function createAction($username, $firstname, $lastname, $password1) {
        $roles = array('Customer');

        // create a account with password an add it to the accountRepository
        $account = $this->accountFactory->createAccountWithPassword($username, $password1, $roles);
        $this->accountRepository->add($account);

        // create person with firstName, lastname and account
        $personName = new \TYPO3\Party\Domain\Model\PersonName('', $firstname, '', $lastname);
        $person = new \TYPO3\Party\Domain\Model\Person();
        $person->setName($personName);
        $person->addAccount($account);
        $this->partyRepository->add($person);

        // authenticate Account
        $authenticationTokens = $this->securityContext->getAuthenticationTokensOfType('TYPO3\FLOW3\Security\Authentication\Token\UsernamePassword');
        if (count($authenticationTokens) === 1) {
            $authenticationTokens[0]->setAccount($account);
            $authenticationTokens[0]->setAuthenticationStatus(\TYPO3\FLOW3\Security\Authentication\TokenInterface::AUTHENTICATION_SUCCESSFUL);
        }

        // add a message and redirect to the login form
        $this->addFlashMessage('Account created.');
        $this->redirect('index', 'Login');
    }

AccountFactory.php

/**
     * @param array  $factorySpecificConfiguration
     * @param string $presetName
     *
     * @return \TYPO3\Form\Core\Model\FormDefinition
     */
    public function build(array $factorySpecificConfiguration, $presetName) {
        $formConfiguration = $this->getPresetConfiguration($presetName);
        $form = new FormDefinition('contactForm', $formConfiguration);

        $page1 = $form->createPage('page1');

        $userName = $page1->createElement('userName', 'TYPO3.Form:SingleLineText');
        $userName->setLabel('Username');
        $userName->addValidator(new \TYPO3\FLOW3\Validation\Validator\NotEmptyValidator());

        $firstName = $page1->createElement('firstName', 'TYPO3.Form:SingleLineText');
        $firstName->setLabel('First Name');
        $firstName->addValidator(new \TYPO3\FLOW3\Validation\Validator\NotEmptyValidator());

        $lastName = $page1->createElement('lastName', 'TYPO3.Form:SingleLineText');
        $lastName->setLabel('Last Name');
        $lastName->addValidator(new \TYPO3\FLOW3\Validation\Validator\NotEmptyValidator());

        $password = $page1->createElement('password', 'TYPO3.Form:PasswordWithConfirmation');
        $password->setLabel('Password');
        $password->addValidator(new \TYPO3\FLOW3\Validation\Validator\NotEmptyValidator());
        $password->addValidator(new \TYPO3\FLOW3\Validation\Validator\StringLengthValidator(array('minimum' => 8)));


        $redirectFinisher = new \My\Package\FormFinishers\ExtendedRedirectFinisher();
        $redirectFinisher->setOptions(
            array(
                'action' => 'create',
                'arguments' => array(
                    'username' => '{userName}',
                    'firstname' => '{firstName}',
                    'lastname' => '{lastName}',
                    'password1' => '{password}'
                )
            )
        );
        $form->addFinisher($redirectFinisher);

        return $form;
    }

ExtendedRedirectFinisher.php

/**
     * Read the option called $optionName from $this->options, and parse {...}
     * as object accessors.
     *
     * if $optionName was not found, the corresponding default option is returned (from $this->defaultOptions)
     *
     * @param string $optionName
     * @return mixed
     * @api
     */
    protected function parseOptionArguments($optionName) {
        $option = $this->options['arguments'][$optionName];
        if (!is_string($option)) {
            return $option;
        }
        $formRuntime = $this->finisherContext->getFormRuntime();
        return preg_replace_callback('/{([^}]+)}/', function($match) use ($formRuntime) {
            return \TYPO3\FLOW3\Reflection\ObjectAccess::getPropertyPath($formRuntime, $match[1]);
        }, $option);
    }

    /**
     * Executes this finisher
     * @see AbstractFinisher::execute()
     *
     * @return void
     * @throws \TYPO3\Form\Exception\FinisherException
     */
    public function executeInternal() {
        $formRuntime = $this->finisherContext->getFormRuntime();
        $request = $formRuntime->getRequest()->getMainRequest();

        $packageKey = $this->parseOption('package');
        $controllerName = $this->parseOption('controller');
        $actionName = $this->parseOption('action');

        $arguments = $this->options['arguments'];
        foreach ($arguments as $key => $argument) {
            $arguments[$key] = $this->parseOptionArguments($key);
        }

        $delay = (integer)$this->parseOption('delay');
        $statusCode = $this->parseOption('statusCode');

        $subpackageKey = NULL;
        if ($packageKey !== NULL && strpos($packageKey, '\\') !== FALSE) {
            list($packageKey, $subpackageKey) = explode('\\', $packageKey, 2);
        }
        $uriBuilder = new \TYPO3\FLOW3\Mvc\Routing\UriBuilder();
        $uriBuilder->setRequest($request);
        $uriBuilder->reset();

        $uri = $uriBuilder->uriFor($actionName, $arguments, $controllerName, $packageKey, $subpackageKey);
        $uri = $request->getHttpRequest()->getBaseUri() . $uri;
        $escapedUri = htmlentities($uri, ENT_QUOTES, 'utf-8');

        $response = $formRuntime->getResponse();
        $response->setContent('<html><head><meta http-equiv="refresh" content="' . $delay . ';url=' . $escapedUri . '"/></head></html>');
        $response->setStatus($statusCode);
        if ($delay === 0) {
            $response->setHeader('Location', (string)$uri);
        }
    }

new.html

{namespace form=TYPO3\Form\ViewHelpers}

<f:layout name="Default" />

<f:section name="Title">New account</f:section>

<f:section name="Content">
    <p>Just fill out the following form to create a new account:</p>

    <form:render factoryClass="My\Package\FormFactories\AccountFactory" />
</f:section>