There's new version of activemq-rar available in Maven repository[1] that corresponds with A-MQ 6.3 R7 patch released in May [2]. And A-MQ 6.3 image is being upgraded to R7 also [3].

[1] https://maven.repository.redhat.com/ga/org/apache/activemq/activemq-rar/5.11.0.redhat-630343/
[2] https://access.redhat.com/jbossnetwork/restricted/softwareDetail.html?softwareId=57981&product=jboss.amq.broker&version=6.3.0&downloadType=securityPatches
[3] https://issues.jboss.org/browse/CLOUD-2589