setRequestContext example

      }

      // Regardless of whether the target is the original one or the overridden       // destination, ensure that all redirects are safe.       if (!($response instanceof SecuredRedirectResponse)) {
        try {
          // SecuredRedirectResponse is an abstract class that requires a           // concrete implementation. Default to LocalRedirectResponse, which           // considers only redirects to within the same site as safe.           $safe_response = LocalRedirectResponse::createFromRedirectResponse($response);
          $safe_response->setRequestContext($this->requestContext);
        }
        catch (\InvalidArgumentException $e) {
          // If the above failed, it's because the redirect target wasn't           // local. Do not follow that redirect. Display an error message           // instead. We're already catching one exception, so trigger_error()           // rather than throw another one.           // We don't throw an exception, because this is a client error rather than a           // server error.           $message = 'Redirects to external URLs are not allowed by default, use \Drupal\Core\Routing\TrustedRedirectResponse for it.';
          trigger_error($message, E_USER_ERROR);
          $safe_response = new Response($message, 400);
        }