Found on os+jvm certification Jenkins job here:
https://jenkins.mw.lab.eng.bos.redhat.com/hudson/view/BxMS/view/BxMS-6.0/view/jBPM/view/all/job/bpms-jbpm-community-os-jvm-matrix/jdk=ibm16,label_exp=RHEL6/lastCompletedBuild/testReport/org.jbpm.compiler.xml.processes/XMLPersistenceTest/testPersistenceOfFullNodes/

org.jbpm.compiler.xml.processes.XMLPersistenceTest.testPersistenceOfFullNodes

Error Message

expected:<... <metaData name="[UniqueId">
<value>_jbpm-unique-528</value>
</metaData>
<metaData name="meta1">
<value>someValue]</value>
</met...> but was:<... <metaData name="[meta1">
<value>someValue</value>
</metaData>
<metaData name="UniqueId">
<value>_jbpm-unique-528]</value>
</met...>

Reproduced afterwards on Jenkins slave:
cd jbpm
git checkout 6.0.x
cd jbpm-flow-builder
export JAVA_HOME=/qa/tools/opt/ibm-java-60
/qa/tools/opt/maven3-latest/bin/mvn clean package -Dtest=org.jbpm.compiler.xml.processes.XMLPersistenceTest

This issue doesn't appear on IBM Java 7, so this makes it less serious.

Expected behavior:
All community unit tests work well on all supported platforms (OS+JVM).

My env:
RHEL 6
IBM Java 6