QPID-5820: [Java QMF2 Plugin] changes to plugin owing to the Java Broker model updates made during 0.29

* Used model getters rather than named attributes wherever possible

Work done by Andrew MacBean <macbean@apache.org> and me.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1607034 13f79535-47bb-0310-9956-ffa450edef68