Just loaded jruby-complete-9.1.15.0.jar from http://jruby.org/download and put it as a single JAR on the JPMS module path. Here it reports as a module with name:

• com.headius.invokebinder

There's a module-info.class in the root of the JAR. I guess this happens when merging dependencies into the complete distro.

"complete" or "all" distro jars should not land on the module path -- but if they do, they should not present themselves as an explicit module nor provide an Automatic-Module-Name in the MANIFEST.

jruby-complete-9.1.14.0.jar is affected too.

jar --describe-module reports:

com.headius.invokebinder jar:file:///[...]/jruby-complete-9.1.15.0.jar/!module-info.class
exports com.headius.invokebinder
requires java.base
requires java.logging