private function createDeleteForm($id)
    {
        if (version_compare(phpversion(), '5.5', '<')) {
            return $this->createFormBuilder(array('id' => $id))
                ->add('id', 'hidden')
                ->getForm();
        }
        else {
            return $this->createFormBuilder(array('id' => $id))
                ->add('id', 'Symfony\Component\Form\Extension\Core\Type\HiddenType')
                ->getForm();
        }
    }