discussed with lukas over lunch. adding a new interface for that method is rather heavy. but changing the existing interface would be a major BC break as any provider implementation would have to implement that new method.

with the proposed semantical tweak on the interface, the worst that can happen is a `E_WARNING` on having foreach(null), then returning an empty collection. @Crell can you agree with this proposal, would that fix the issue for you? i guess for drupal you could either drop the method, or if you want to keep it, add `if (null === $names) return $this->getAllRoutes();` to your provider for compatibility with the DynamicRouter.