Update Expressjs dependency to 4.x

I have a question about compoundjs that will maintainers consider upgrading to expressjs 4.x on roadmap?
I'm looking for fresh framework which is using expressjs 4.x but seems most of them stay using 3.x.

Thank you.

Check the package.json for the current express version and review the Express 4.x migration guide for breaking changes. Look at the compound codebase to see where express is integrated, particularly in server setup and middleware. Test the upgrade by updating the dependency and running existing tests to identify failures.

索引モデルが issue の本文から書いたものです。