[master 9c437b0] upgrades EMS from 1.2.16 to 1.3 in the root pom.
Similarly, commit dc4a80e upgrades EMS to 1.3 on the release_jon3.x branch.
Once you've pulled either of these commits, make sure to:
cd rhq mvn -N install cd modules/plugins/jmx mvn clean install
Otherwise, you'll end up with two versions of the EMS jar inside the jmx plugin jar, which will have unpredictable, and most likely bad, results.