Group and nest routes in Symfony 3

I currently work on a Symfony Project with a large number of namespaces and Bundles. Many of them share the same base route like so:

# /app/config/routing.yml
something:
  resource: "@SomethingBundle/Controller/"
  prefix:   /admin/something
  type:     annotation

Now, at least 10 other bundles use the /admin prefix as well, so I was wondering if there would be a way to group and nest them? I imagine something like this (pseudocode):

admin:
  prefix: /admin
  nested_resources:
    - something:
        resource: "@SomethingBundle/Controller/"
        prefix:   /something
        type:     annotation
    ...