CraueFormFlowBundle fill previous data when navigating steps

RegistrationController.php

<?php

namespace Ormigo\Bundle\UserBundle\Controller;

use Symfony\Component\HttpFoundation\RedirectResponse;
use FOS\UserBundle\Controller\RegistrationController as Controller;

class RegistrationController extends Controller
{
    // .. some more actions

    public function merchantWizardAction()
    {
        $formData = $data = array(); // Should be some actual data model

        /* @var $flow \Craue\FormFlowBundle\Form\FormFlow */
        $flow = $this->container->get('ormigo_user.form.merchant_register_wizard.flow');
        $flow->bind($data);

        // Retrieve form data for the current step
        if ($flowData = $this->container->get('session')->get($flow->getSessionDataKey())) {
            if (!empty($flowData[$flow->getCurrentStep()])) {
                $formData = $flowData[$flow->getCurrentStep()];
            }
        }

        // Form of the current step
        $form = $flow->createForm($formData);
        if ($flow->isValid($form)) {
            $flow->saveCurrentStepData();

            if ($flow->nextStep()) {
                $formData = array(); // Should be initialized according to the data model

                // Refresh form data based on the new step
                if (!empty($flowData[$flow->getCurrentStep()])) {
                    $formData = $flowData[$flow->getCurrentStep()];
                }

                // Form for the next step
                $form = $flow->createForm($formData);
            } else {
                // Last step done!
                // Persist data, send emails, push messages, you name it ..
            }
        }

        return $this->container->get('templating')->renderResponse('UserBundle:Registration:register_merchant_wizard.html.'.$this->getEngine(), array(
            'form' => $form->createView(),
            'flow' => $flow,
        ));
    }
}