Sylius\Bundle\OrderBundle\Form\Type\CartType::buildForm PHP Method

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder->add('items', CollectionType::class, ['entry_type' => CartItemType::class, 'allow_add' => true, 'allow_delete' => true, 'by_reference' => false, 'label' => 'sylius.form.cart.items']);
    }