org.w3c.dom package classpath and modul path collision

[efc-mw]

The project dependency to dom4j pulls in an optional runtime dependency of jaxen 1.1.6. This old library contains parts of the org.w3c.dom package. This result in classpath clashes with the package now on the JDK module path since Java 9. If this optional runtime dependency of dom4j for xpath expressions is not used, please exclude the jaxen jar from the dependencies.