URL rewrites for submodules

Hi,

I recently learned about rewriting URLs. Pretty cool feature. Learned about it here: https://jonhnnyweslley.net/blog/how-to-rewrite-git-urls-to-clone-faster-and-push-safer/

But I've been doing some testing, and this feature does not seem to work for git submodules. Is it like that by design, so are there technical or practical limitation why we would not like to have this feature on submodules too?

If it's not by design, would you consider a contribution adding this feature? What should I then pay attention at? For example, should there be an option to enable/disable it for submodules, something like:

[url "http://new.url.example.com"]
     insteadOf = "old.url.example.com"
     submodules = true

-- Toon