symfony2 dynamic validator constraints

CheckoutFullType.php

<?php

namespace n3b\Bundle\Shop\Form;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilder;
use Symfony\Component\Form\FormEvents;

class CheckoutFullType extends AbstractType
{

    public function buildForm(FormBuilder $builder, array $options)
    {
        $builder->add('deliver', 'checkbox')
            ->add('user_save', 'checkbox')
            ->add('checkout', new CheckoutType());

        $builder->addEventSubscriber(new EventSubscriber\PreBindDataSubscriber());
        $builder->addValidator(new Validator\CheckoutDeliveryValidator());
    }

    public function getDefaultOptions(array $options)
    {
        return array(
            'validation_groups' => array('pass_through'),
            'data_class' => 'n3b\Bundle\Shop\Entity\Customer',
        );
    }
}

Customer.php

<?php

namespace n3b\Bundle\Shop\Entity;

use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Validator\Constraints as Assert;
use Doctrine\Common\Collections\ArrayCollection;
use n3b\Bundle\Shop\Model\Customer as BaseCustomer;

/**
 * @ORM\Entity
 */
class Customer extends BaseCustomer
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;
    /**
     * @ORM\Column(unique="true", nullable="true")
     * @Assert\NotBlank(groups={"registration"})
     * @Assert\Blank(groups={"pass_through"})
     */
    protected $login;
}

Form.php

<?php 

namespace Symfony\Component\Form;

use Symfony\Component\Form\Event\DataEvent;
use Symfony\Component\Form\Event\FilterDataEvent;
use Symfony\Component\Form\Exception\FormException;
use Symfony\Component\Form\Exception\UnexpectedTypeException;
use Symfony\Component\Form\Exception\TransformationFailedException;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\EventDispatcher\EventDispatcherInterface;

class Form implements \IteratorAggregate, FormInterface
{

...
    //этого метода нет в дефолтной комплектации
    public function setAttribute($name, $value)
    {
        $this->attributes[$name] = $value;
    }
}

PreBindDataSubscriber.php

<?php

namespace n3b\Bundle\Shop\Form\EventSubscriber;

use Symfony\Component\Form\FormEvents;
use Symfony\Component\Form\Event\DataEvent;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

class PreBindDataSubscriber implements EventSubscriberInterface
{

    public function onPreBindData(DataEvent $event)
    {
        $data = $event->getData();
        if(isset($data['user_save']))
            $event->getForm()->get('checkout')->get('customer')->setAttribute('validation_groups', array('registration'));
    }

    static public function getSubscribedEvents()
    {
        return array(FormEvents::PRE_BIND => 'onPreBindData');
    }
}

Я не стал там ковыряться, решил инициализировать модель после байнда:

    $form = $this->services['ff']->create(new CheckoutFullType());

    if ($this->services['request']->getMethod() == 'POST') {
        $form->bindRequest($this->services['request']);
        $checkout = $form->get('checkout')->getData();

при таком раскладе в onPreBindData все поголовно в нулях.
По guesser'ам ждем фиксов. Пока накидал цепочку инжектов опций, начиная от билдера и заканчивая непосредственно guesser'ами.