src/TwbBundle/Form/View/Helper/TwbBundleFormCollection.php
public function renderTemplate(CollectionElement $collection)
    {
        if (false != ($sElementLayout = $collection->getOption('twb-layout'))) {
            $elementOrFieldset = $collection->getTemplateElement();
            $elementOrFieldset->setOption('twb-layout', $sElementLayout);
        }

        return parent::renderTemplate($collection);
    }
public function renderTemplate(CollectionElement $collection)
    {
        if (false != ($sElementLayout = $collection->getOption('twb-layout'))) {
            $elementOrFieldset = $collection->getTemplateElement();
            $elementOrFieldset->setOption('twb-layout', $sElementLayout);
        }

        return parent::renderTemplate($collection);
    }
Only render a template

@param CollectionElement $collection
@return string