Sylius\Bundle\PromotionBundle\Form\Type\Core\AbstractConfigurationCollectionType::buildForm PHP Method

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $prototypes = [];
        foreach (array_keys($this->registry->all()) as $type) {
            $prototypeOptions = array_replace(['configuration_type' => $type], $options['entry_options']);
            $form = $builder->create($options['prototype_name'], $options['entry_type'], $prototypeOptions);
            $prototypes[$type] = $form->getForm();
        }
        $builder->setAttribute('prototypes', $prototypes);
    }