Symfony2 Collection Type with default value support by prototype_data option

gistfile1.php

<?php
 
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
 
class CollectionPrototypeDataType extends AbstractType
{
    /**
     * {@inheritdoc}
     */
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        parent::buildForm($builder, $options);
 
        if (null !== ($prototypeFormBuilder = $builder->getAttribute('prototype'))) {
            /** @var $prototypeFormBuilder FormBuilderInterface */
            $prototypeFormBuilder->setData($options['prototype_data']);
        }
    }
 
    /**
     * {@inheritdoc}
     */
    public function getName()
    {
        return 'collection';
    }
 
    /**
     * {@inheritdoc}
     */
    public function getParent()
    {
        return 'collection';
    }
}

What does the service config look like for this form type?

I think extending collection with a type with the name collection causes an infinite loop in 2.5.

I've forked this gist and converted it to a form type extension.
see: https://gist.github.com/jumika/e2f0a5b3d4faf277307a