Java: Artifact archiving must be able to find jars in submodules

Created by: ralphlange

Reported by @mrkraimer:

Building PR epics-base/exampleJava#3 on CloudBees failed with:

...
Archiving artifacts
ERROR: No artifacts found that match the file pattern "target/.jar". Configuration error?
ERROR: ‘target/.jar’ doesn’t match anything, but ‘database/target/*.jar’ does. Perhaps that’s what you mean?
Build step 'Archive the artifacts' changed build result to FAILURE

This repo has submodules. The jenkins job should find artifacts in submodules when archiving the artifacts.