Params.unapply missing explicit type, doesn't compose, and has lying docs

[kenbot]

Hi there,
Couldn't find a duplicate, searching for "Params" or "unapply", so raising an issue.

The documentation of unfiltered.request.Params.unapply indicates that it destructures to (Map[...], HttpRequest). This would allow the pattern to be composed with other patterns, since they can be nested into the HttpRequest.

However, contrary to the usual recommended style for public methods, there is no explicit type given. The inferred type actually destructures to only a Map[...], preventing the pattern from being composed, and rather embarrassing the documentation. The behaviour appears to be in all the versions I looked at on Github.

Cheers,
Ken

[kenbot]

(Happy to pony up a PR if there's some sort of consensus on what to do.)

[hamnis]

We cant change how Params work now, but we could add a ChainableParams extractor or something like that to enable this.

Otherwise I would recommend using unfiltered-directives to chain this better.