Form Categorias Recursiva

class CompanyType
...
$builder
->add('extra', 'entity', array(
                    'class' => '...\Entity\Category',
                    'property' => 'categoryLanguage', <--- Entidade a qual fica o rotulo
                    'mapped' => false,
                    'attr' => array('class' => 'category'),
                    'query_builder' => function(EntityRepository $repository){
                            return $repository->createQueryBuilder('c')
                                        ->where('c.subcategories is null');
                        }
                )
            )
->add('categories', 'entity', array(
                    'class' => '...\Entity\Category',
                    'property' => 'categoryLanguage', <--- Entidade a qual fica o rotulo
                    'empty_value' => 'Selecione...',
                    'multiple' => true,
                    'choices' => [],
                    'by_reference' => false,
                    'attr' => array('class' => 'subcategory')
                )
            )

->addEventListener(FormEvents::PRE_SUBMIT, function(FormEvent $event){
                $form = $event->getForm();
                $data = $event->getData();
                $form->add('categories', 'entity', array(
                        'class' => 'BemLocalizado\Bundle\CoreBundle\Entity\Category',
                        'property' => 'categoryLanguage',
                        'empty_value' => 'Selecione...',
                        'multiple' => true,
                        'by_reference' => false,
                        'attr' => array('class' => 'subcategory'),
                        'data' => array_key_exists('categories', $data) ? $data['categories'] : null
                    )
                );
            });