Akka-http: Should response/request.header[T] be ModeledCustomHeader aware?

[ktoso]

This requires a bunch of hacks though, as the impl that makes it work in akka-http is the HeaderMagnet infra which we do not have immediately available in akka-http-core, and I'm not sure if we want to have it there.

https://github.com/akka/akka-http/blob/master/akka-http/src/main/scala/akka/http/javadsl/server/directives/HeaderDirectives.scala#L84

We can make it work using some smarts however making it possible for Java should likely use the partial function style as we suggest anyway for the routing DSL for it.

[czare1]

At least the documentation should mention that it won't work this way.