Как использовать в формах choices с ArrayCollection, но не с Entity, а с обычным классом?

class ChoicesCollectionToArrayTransformer implements DataTransformerInterface
{

    private $choiceList;

    public function __construct(ChoiceListInterface $choiceList)
    {
        $this->choiceList = $choiceList;
    }

    public function transform($collection)
    {
        if (null === $collection) {
            return array();
        }

        if (is_array($collection)) {
            return $collection;
        }

        if (!$collection instanceof Collection) {
            throw new TransformationFailedException('Expected a Doctrine\Common\Collections\Collection object.');
        }

        return $this->choiceList->getValuesForChoices($collection->toArray());
    }

    public function reverseTransform($array)
    {
        if ('' === $array || null === $array) {
            $array = array();
        } else {
            $array = (array) $array;
        }

        $choices = $this->choiceList->getChoicesForValues($array);

        if (count($choices) !== count($array)) {
            throw new TransformationFailedException('Could not find all matching choices for the given values');
        }

        return new ArrayCollection($choices);
    }
}

$skillsChoiceList = new ObjectChoiceList(
            $this->skillManager->getAllSkills()->toArray(),
            'name',
            array(),
            null,
            'alias'
        );

$builder ->add('skills', 'choice', array(
                'choice_list' => $skillsChoiceList,
                'multiple' => true
            ));

$builder->get('skills')->resetViewTransformers()->addViewTransformer(new ChoicesCollectionToArrayTransformer($skillsChoiceList));