public function prePersist(LifecycleEventArgs $event)
    {
        $user = $event->getEntity();

        if (!($user instanceof User)) {
            return;
        }

        $pass = $user -> getPlainPassword();

        if (!empty($plainPassword)) {
            $encoder = $this->get('security.password_encoder');
            $encoded = $encoder->encodePassword($user, $pass);
            $user->setPassword($encoded);
        }
    }