Github user afs commented on the issue:
https://github.com/apache/jena/pull/401
jdeps complains about oaj.dboe so having a common automatic-moulde-name
seems not to work.
Clearing that out and xerces, then
/usr/lib/jvm/java-9-openjdk-amd64/bin/jdeps -R --module-path libx
-filter:module -m org.apache.jena.arq
shows (reformatted from jdeps)
org.apache.jena.atlas.data -> org.apache.jena.atlas
org.apache.jena.base---
