The intention of this enhancement is for monitoring purposes.
It would be nice to be able to view from JMX which user is using a given connection. This could be for example a new read-only attribute 'UserName' on MBean org.apache.activemq.broker.jmx.ConnectionViewMBean.
The Same idea applies to org.apache.activemq.broker.jmx.SubscriptionViewMBean and org.apache.activemq.broker.jmx.ProducerViewMBean.
This property should be controlled however by configuration on the BrokerService to enable or disable this user name tracking, the default value should be to disable this. When disabled the reported user name from these beans would be null.