Access to systemAdminMenuBlockPage is denied if it contains routes using the url attribute

I can confirm that the fix works.

I followed these steps.
Install Drupal 11
Create a custom module test link
Create the route and the menu link files as mentioned above.
Enabled the module.
Access the following url: /admin/test-link

Without the fix, I couldn't access the page.

After the fix was applied, I could access it.

One comment on the MR.

I confirm that after the code review changes the issue still fixed.

Same steps followed of comment #5

Access denied in without the fix.

Could access with the fix applied.

This looks nearly ready - I think we can use API rather than exceptions to skip unrouted routes in the child link checking...