ClasspathHellDuplicatesCheckRule fails on Oracle Java (only Oxygen & Fluorine; Neon OK)

as per the discussion on and analysis in the "[infrautils-dev] infrautils build : ClasspathHellDuplicatesCheckRule : Classpath errors detected " thread on https://lists.opendaylight.org/pipermail/infrautils-dev/2018-December/thread.html, the ClasspathHellDuplicatesCheckRule fails when you run on Oracle Java instead of OpenJDK.

The email thread describes the mystery why this could have failed but only for our friends at Ericsson and never for other developer and on the opendaylight.org; I've just been able to confirm that this is due to running under Oracle Java instead of OpenJDK, and locally reproduced this - logs attached.

This problem only affects Oxygen & Fluorine; Neon is OK because https://git.opendaylight.org/gerrit/#/c/76625/ completely changed the implentation, to using Classgraph instead jHades.