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. I've raised https://github.com/scala/scala-xml/issues/367 https://github.com/scala/scala-collection-compat/issues/263 https://github.com/scala/scala-java8-compat/issues/168 https://github.com/scala/scala-collection-contrib/issues/65 https://github.com/scala/scala-parallel-collections/issues/82 and https://github.com/scala/scala-parser-combinators/issues/248 as I wasn't aware of this project.