It seems upgrading to 9.1.16 isn't enough [1], we need at least JRuby 9.2.1 for a good compatibility with Java 9, 10 and 11.
https://github.com/jruby/jruby/issues/5446#issuecomment-438732326 __ This is the maintainer address of Debian's Java team <https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/pkg-java-maintainers>. Please use [email protected] for discussions and questions.
