I can access other MXBean types, such as the RuntimeMXBean, but not the GarabageCollectorMXBean:
JMXConnector connector = JMXConnectorFactory.connect(new JMXServiceURL("service:jmx:rmi:///jndi/rmi://coretest:1542/jmxrmi"));
MBeanServerConnection mbs = connector.getMBeanServerConnection();
GarbageCollectorMXBean gc = ManagementFactory.newPlatformMXBeanProxy(mbs, ManagementFactory.GARBAGE_COLLECTOR_MXBEAN_DOMAIN_TYPE, GarbageCollectorMXBean.class);
and the result is
Exception in thread ...