Challenge shouldn't require realm

[kapunga]

org.http4s.Challenge requires the realm parameter, however the WWW-Authenticate Directive doesn't appear to require it.

[kapunga]

I'm going to open a PR to make realm optional.

[kapunga]

Okay, so digging in a little further, it seems a bit more complicated. realm is required for the Basic challenge types, but not others. Additionally there are other parameters that are required on some, but not on others. Additionally the token68 token that can appear by itself on some challenges and it does not take a value, and therefore doesn't fit into a map. Not to mention, Challenge is very stringly typed.

I think the proper way to fix this would be to turn Challenge into a sealed trait with the different challenge schemes and parameters with an apply(scheme: String, realm: String, params: Map[String, String] = Map.empty) method on the companion object for backwards compatibility.

I'd love to hear other opinions.

[armanbilge]

turn Challenge into a sealed trait with the different challenge schemes

This seems like a good direction to go in.

for backwards compatibility.

Just changing Challenge from a case class to a sealed trait is already breaking binary compatibility. So these changes would have to target the main branch and I don't think it's worth working too hard to preserve other forms of compatibility.