ZF2 form from doctrine entity & annotations

Account.php

<?php

namespace Application\Entity;

use Doctrine\ORM\Mapping as ORM;
use Zend\Form\Annotation;

/**
 * Class Account
 * @package Application\Entity
 * @ORM\MappedSuperclass
 */
class Account
{

    /**
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     * @ORM\Column(type="integer")
     * @Annotation\Exclude
     */
    protected $id;

    /**
     * @ORM\Column(type="string")
     * @Annotation\Type("Zend\Form\Element\Text")
     * @Annotation\Required({"required":"true" })
     * @Annotation\Filter({"name":"StripTags"})
     * @Annotation\Validator({"name":"StringLength", "options":{"min":"1"}})
     * @Annotation\Options({"label":"Username:"})
     */
    protected $username;

    /**
     * @ORM\Column(type="string")
     * @Annotation\Type("Zend\Form\Element\Password")
     * @Annotation\Required({"required":"true" })
     * @Annotation\Validator({"name":"StringLength", "options":{"min":"6"}})
     * @Annotation\Options({"label":"Password:"})
     */
    protected $password;

    /**
     * @Annotation\Type("Zend\Form\Element\Submit")
     * @Annotation\Attributes({"value":"Submit"})
     */
    protected $submit;

    /**
     * @param mixed $password
     */
    public function setPassword($password)
    {
        $this->password = md5($password);
    }

    /**
     * @param mixed $username
     */
    public function setUsername($username)
    {
        $this->username = $username;
    }

    /**
     * @return mixed
     */
    public function getPassword()
    {
        return $this->password;
    }

    /**
     * @return mixed
     */
    public function getUsername()
    {
        return $this->username;
    }
}

IndexController.php

<?php

namespace Application\Controller;

use Application\Entity\User;
use DoctrineORMModule\Form\Annotation\AnnotationBuilder;
use Zend\Mvc\Controller\AbstractActionController;
use DoctrineModule\Stdlib\Hydrator\DoctrineObject as DoctrineHydrator;
use Zend\View\Model\ViewModel;

/**
 * Class IndexController
 * @package Application\Controller
 */
class IndexController extends AbstractActionController
{
    public function indexAction()
    {
        /** @var $em \Doctrine\ORM\EntityManager */
        $em = $this->getServiceLocator()->get('Doctrine\ORM\EntityManager');

        if (($user = $em->find('Application\Entity\User', 1)) === null) {
            $user = new User();
        }

        $builder    = new AnnotationBuilder($em);
        $form       = $builder->createForm($user);
        $form->setHydrator(new DoctrineHydrator($em, 'Application\Entity\User'))->bind($user);
        $request = $this->getRequest();

        if ($request->isPost()) {
            $form->setData($request->getPost());

            if ($form->isValid()) {
                $em->persist($user);
                $em->flush();
                return $this->redirect()->toRoute('home');
            }
        }

        return new ViewModel(array('form'=>$form));
    }
}

User.php

<?php

namespace Application\Entity;

use Doctrine\ORM\Mapping as ORM;
use Zend\Form\Annotation;

/**
 * Class User
 * @package Application\Entity
 * @ORM\Entity
 * @ORM\Table(name="users")
 * @Annotation\Name("user")
 */
class User extends Account
{

    /**
     * @ORM\Column(type="string")
     * @Annotation\Type("Zend\Form\Element\Email")
     * @Annotation\Required({"required":"true" })
     * @Annotation\Filter({"name":"StripTags"})
     * @Annotation\Validator({"name":"StringLength", "options":{"min":"1"}})
     * @Annotation\Validator({"name":"EmailAddress"})
     * @Annotation\Options({"label":"E-Mail:"})
     */
    protected $email;



    public function setEmail($param)
    {
        $this->email = $param;

    }

    /**
     * @return mixed
     */
    public function getEmail()
    {
        return $this->email;
    }
}