Add Automatic-Module-Name to MANIFEST.INF

[schrepfler]

In order to increase compatibility on JDK versions with modules consider adding Automatic-Module-Name in the MANIFEST.INF along the lines of akka/akka#23960 or perhaps even implement properly the module-info descriptor.

[ashawley]

I predict this may be something that could be handled upstream in the shared sbt plugin https://github.com/scala/sbt-scala-module/

[schrepfler]

Ah, wasn't aware there's a shared build plugin. I'll raise it upstream, thanks.

[ashawley]

We'll see. We can keep this open, though.

[ashawley]

I don't know enough, but maybe it's even something that would be done in sbt or even Scala itself.

[SethTisue]

fixed by #518