I don't understand the use case as it always returns the first matching resource.

The default behaviour is to return the first match , but if you pass the third parameter to locateResource as false, then it returns an array of matching resources

Closing as there is no activity, and I'm not sure this works in practice, as the glob will miss overridden resources. Feel free to reopen of course.

Would the overridden resource not already be resolved at this point?

nope. The bundle inheritance is gone, but this locator still allows project-level overriding.

But by the time it does the file_exists check, should it not aleady have resolved the overridden resource, to know which file and path to check?

but for a glob, each one of the match could be overridden independently (and this PR won't handle it).