Symfony version(s) affected: Tested with 5.1.5

Description
I ran into this issue when setting up the FOSRestBundle.
https://symfony.com/doc/3.x/bundles/FOSRestBundle/versioning.html#how-to-match-a-specific-version-in-my-routing

When I tried the condition mentioned there and sent a request to http://localdomain.tld/api/v1/element/get/123, it resulted in a route not found exception. Changing the match value from 'v1' to null resulted in a successful response. It seems the request attributes are not available for the condition.

How to reproduce

Since I figured it might be related to an installed bundle, I set up a separate skeleton with the minimal required composer packages and reproduced the issue.

mkdir project_folder
cd project_folder
composer create-project symfony/skeleton .
composer require annotations
composer require symfony/expression-language

Create src/Controller/TestController.php

<?php

namespace App\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Routing\Annotation\Route;

/**
 * @Route("/api/{version}/element")
 */
class TestController extends AbstractController
{
    /**
     * @param Request $request
     * @param int $id
     * @Route("/get/{id}", condition="request.attributes.get('version') == 'v1'")
     */
    public function getById(Request $request, int $id): JsonResponse
    {
        $data = [
            [
                'version' => $request->attributes->get('version'),
            ]
        ];
        return new JsonResponse($data);
    }
}

Request the action by navigating to http://localdomain.tld/api/v1/element/get/123
This results in: No route found for "GET /api/v1/element/get/123"

Changing 'v1' to null in the condition and reloading the request results in:

[{"version":"v1"}]

So apparently the version attribute is there, but not for the condition.