public function getByRegistrationToken($code)
    {
        $builder = $this->createQueryBuilder('u');

        return $builder
            ->where('u.registrationConfirmToken.id=:code')
            ->andWhere($builder->expr()->isNotNull('u.registrationConfirmToken.id'))
            ->setParameter('code', $code)
            ->setMaxResults(1)
            ->getQuery()
            ->getOneOrNullResult()
        ;
    }