Stupid me:
I was still on sbt 0.7. Don't know if you can change jetty
configuration in this version, so I (just) migrated to sbt 0.11. Quite
some work.
> stealing Tim's answer, to enable ssl it may be easier to simply use
>
> configurationFiles in container.Configuration := Seq(file("jetty.xml"))
> to specify your own jetty conf file
If anyone has a similar problem, DON'T FORGET:
customConfiguration in container.Configuration := true
Greetings,
Ben