* Include Scala 3 in cross-build
sbt cross-building sometimes behaves surprisingly, so this does not work
yet: when switching to 3.0.1-RC1 it still tries to build the modules
that do not support that version yet, even though they are 'excluded'.
This also currently breaks cross-publishing, so we cannot merge this.
Once this works we should add a note to the documentation clarifying
that the Scala 3 artifacts are experimental.
* Fix jackson test dependency
* Don't publish docs for scala3 artifacts for now
* Publish empty doc packages for Scala 3 artifacts
* Unfortunately it seems the jdk9-only tests could not actually be compiled.
With these changes those can actually be compiled and ran again.
* Always link to jdk11 for java.* javadocs
* Update sbt-paradox-akka to fix linking to inner classes for javadoc
* Add CopyrightHeader support for sbt-boilerplate plugin.
* Add CopyrightHeader support for `*.proto` files.
* Add regex match for both `–` and `-` for CopyrightHeader.
* Add CopyrightHeader support for sbt build files.
* Update copyright from 2018 to 2019.
