Can't get implementing classname for JSR77 MBean

The following exception are thrown when asking the MBean server for the classname implementing "jboss.jsr77:j2eeType=WebModule,name=MyWar.war,J2EEServer=default".

It should be a legal call. Why are the code clearly states it's illegal?

java.lang.IllegalStateException: JBAS019905: Should not get called

at org.jboss.as.jsr77.managedobject.J2EEDeployedObjectHandlers$J2EEModuleHandler.queryObjectNames(J2EEDeployedObjectHandlers.java:245)

at org.jboss.as.jsr77.managedobject.BaseHandler.getMBeanInfo(BaseHandler.java:64)

at org.jboss.as.jsr77.managedobject.J2EEDeployedObjectHandlers.getMBeanInfo(J2EEDeployedObjectHandlers.java:147)

at org.jboss.as.jsr77.managedobject.ManagedObjectHandlerRegistry.getMBeanInfo(ManagedObjectHandlerRegistry.java:112)

at org.jboss.as.jsr77.subsystem.JSR77ManagementMBeanServer.getMBeanInfo(JSR77ManagementMBeanServer.java:179)

at org.jboss.as.jmx.PluggableMBeanServerImpl.getMBeanInfo(PluggableMBeanServerImpl.java:212)

The error can easily be triggered by using JConsole to browse the same MBean.