How can I avoid lower-casing of HTTP headers?

[t-rapp]

Summary

I have re-implemented some of my HTTP service applications using axum together with tower-http. Unfortunately there is a compatibility problem with one of the external HTTP clients. After some testing I would like to exclude that the issue happens because the client is treating HTTP response headers in a case-sensitive way.

Is there a possibility to avoid the automatic lower-casing of header names when building a response?

axum version

0.6.20

[t-rapp]

I managed to change my original HTTP service implementation so it uses lowercase header names, too. That way I could exclude that the issue happens because of a case-sensitive handling of headers in specific HTTP clients.