Looking at the server log the failure is in some complex code in ConfigurationManager and its use of CriteriaQuery and what looks like override of the Criteria searchExpression. Not sure if this is still an issue, an issue in RHQ code, or something defined in the JDG plugin. Assigning to Stefan since he was last to update what looks like the critical section. Stefan, I think Tristan Tarrant is the JDG plugin person if you need a contact.
Discussed with the JDG team and the plugin code changed considerably since the bug was reported. Please re-test this bug with JON 3.2 CP3 or JON 3.3.0.
Ok, taking into account that both products and prepared plug-in pack made _significant_ step(s) forward since January, I set this BZ to VERIFIED. Desired functionality is working with JDG 6.4.0 ER1 + its plug-ins and JON 3.3.0 ER4. This version setting will go out around DEC/JAN 2015 and this functionality will be fully prepared, tested and stable.