Surchar de UrlHelper cakephp3 ne fonctionne pas

Bonjour,
Voic mon code.
namespace App\View\Helper;

use Cake\View\Helper;

class MyUrlHelper extends Helper\UrlHelper
{

public function build($url = null, $full = false) {

    if(is_array($url)){
        if(!isset($url['language']) && isset($this->request->params['language'])) {
            if($url == '#') 
            {
                $url = array();
            }
            $url['language'] = $this->request->params['language'];
        }
    }
   return parent::build($url, $full);
}

}