How to inhibit Soap Security headers "mustUnderstand" attribute in a Symfony2 controller

I never managed to make native PHP SoapServer class to handle "understand" soap:Security header as expected with mustUnderstand attribute. But some WS tools like SoapUI automatically set it to "true" or "1" and I needed to make a work around to avoid Soap Fault : "SOAP-ENV:MustUnderstand / Header not understood"

Here is a controller action that inhib mustUnderstand attribute :

   public function ordersFollowUpAction()
   {
      $request = $this->getRequest();

      //This deletes mustUnderstand attribute from raw request content
      $decodedRequest = preg_replace('/ ([-\w]+\:)?(mustUnderstand=")(1|true)(")/', '', $request->getContent());

      $server = new \SoapServer(__DIR__ . '/../Resources/public/wsdl/MyWsdl.wsdl');

      $server->setObject($this->get('my_webservice'));

      $response = new Response();
      $response->headers->set('Content-Type', 'text/xml; charset=UTF-8');

      try
      {
         ob_start();
         //This explicitely passes clear request content to the service handler
         $server->handle($decodedRequest);
         $response->setContent(@ob_get_clean());
      }
      catch (\Exception $e)
      {
         $this->get('logger')->err($e->getMessage());
         $response->setContent('An error occured, please contact our support service.');
      }

      return $response;
   }