Exemple overriding FormRow Helper for adding "required" class to element's label if it has required attribute

ExempleFormRow.php

<?php
/**
 * This class ovveride FormRow view helper
 * The file should be in "module/Application/src/Application/Form/View/Helper" directory
 */
namespace Application\Form\View\Helper;
class ExempleFormRow extends \TwbBundle\Form\View\Helper\TwbBundleFormRow{
	public function render(\Zend\Form\ElementInterface $oElement){	
		if($oElement->getAttribute('required') === true){
			$aLabelAttributes = $oElement->getLabelAttributes()?:$this->labelAttributes;
			if(empty($aLabelAttributes['class']))$aLabelAttributes['class'] = 'required';
			elseif(strpos($aLabelAttributes['class'], 'required') === false)$aLabelAttributes['class'] .= ' required';
			$oElement->setLabelAttributes($aLabelAttributes);
		}
		return parent::render($oElement);
	}
}

module.config.php

<?php
//Config for Application module
return array(
	//...
	'view_helpers' => array(
		'invokables' => array(
			//Define formRow service
			'formRow' => 'Application\Form\View\Helper\ExempleFormRow',
		)
	)
	//...
);