只有当用户代理符合条件时，Symfony才会进入路由？

The problem

I have a web-server that generates an index page that runs Angular, which uses API calls to display data.

I have meta tags which are being set by Angular API calls too.

Now if I will post my website on Facebook, the tags will not be initialized because Facebook scrawler does not support Javascript.

Solution Detect Facebook user-agent server-sided, and dedicate specific routes that will use a controller action that returns an index page already initialized with that meta data that facebook needs, using the API calls server sided.

I have tried using the condition option that I read here in Symfony router but I am getting the following error:

Resources/config/routing.yml"
   contains unsupported keys for "bot_facebook_post": "condition"

And that's how my route looks in yml:

bot_facebook_post:
    pattern: /locations/{location}
    condition: "request.headers.get('User-Agent') matches 'facebookexternalhit/1.1'"
    defaults: {
        _controller: Main:bot, slug: ""
    }