[2.3] CS Fixes

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | N/A
| License       | MIT
| Doc PR        | N/A

##### This pull request provides some cs fixes.
I don't like this empty comment. I'm not sure where this is done in other places in Symfony but I'd prefer a "real" empty class as I don't see what this empty comment brings us. Can you remove it here and in other places if this is indeed used elsewhere in the code? Thanks.