QPID-6136: [Java Broker] Set permitted nodes on replica BDB HA VHN only when they are changed

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1630080 13f79535-47bb-0310-9956-ffa450edef68
QPID-6137: Enhance JMXManagementPlugin implementation and add extra logging when InstanceAlreadyExistsException is thrown from JMX on creation of VH MBean

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1630081 13f79535-47bb-0310-9956-ffa450edef68