I am sure that there is 6.4.0.ER1 installed on agent machines, however, JON gui reports there is 6.3.0.GA version of JDG server. This is wrong and I need to look at the cause of this issue. The strange thing is that in current JDG tag/branch there is NO "6.3.0.GA" string so I suspect maybe JON decisioning mechanisms or interference with EAP server or EAP plugin. No JIRA this time, product-related issue.
We state in server_home/version.txt: Red Hat JBoss Enterprise Application Platform - Version 6.3.0.GA Which obviously should be: Red Hat JBoss Data Grid - Version 6.4.0 (+ current release) However, this does not need to solve the problem completely. Experimenting...
Done with experimenting... This works pretty well. We need to state proper product name and version in version.txt file in server_home folder. That's all. Just a note: https://github.com/rhq-project/rhq/blob/master/modules/plugins/jboss-as-7/src/main/java/org/rhq/modules/plugins/jbossas7/BaseProcessDiscovery.java#L688 explain how version discovery works in RHQ.
version.txt file comes from EAP and needs to be removed.
This has been fixed and works like a charm in 6.4.0.ER8 build. Thanks Tristan and Dave!