getChallenger example

      }
    }

    return $result;
  }

  /** * {@inheritdoc} */
  public function challengeException(Request $request, \Exception $previous) {
    $provider_id = $this->getChallenger($request);

    if ($provider_id) {
      $provider = $this->authCollector->getProvider($provider_id);
      return $provider->challengeException($request, $previous);
    }
  }

  /** * Returns the id of the authentication provider for a request. * * @param \Symfony\Component\HttpFoundation\Request $request * The incoming request. * * @return string|null * The id of the first authentication provider which applies to the request. * If no application detects appropriate credentials, then NULL is returned. */