When try to enable JPA statistics on a application from JON UI, it always reconfigure it to undefined?

Issue

• When try to enable JPA statistics on a application from JON 3.2.3 UI, it always reconfigure it to undefined? Why?
  the JON agent logs shows following warning messages :

WARN  [InventoryManager.discovery-1] (rhq.core.pc.inventory.InventoryManager)- Failure during discovery for [Query Cache] Resources - failed after 107 ms.
java.lang.Exception: Discovery component invocation failed.
    at org.rhq.core.pc.util.DiscoveryComponentProxyFactory$ComponentInvocationThread.call(DiscoveryComponentProxyFactory.java:309)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)
Caused by: java.lang.IllegalArgumentException: Plugin error: Resource key [deployment=rhq.ear,subdeployment=rhq-core-domain-ejb3.jar,subsystem=jpa,hibernate-persistence-unit=rhq.ear/rhq-core-domain-ejb3.jar#rhqpu,query-cache=SELECT_space_COUNT_left_paren__star__right_paren__newline_FROM_space_AlertDefinition_space_alertdefinition_newline_WHERE_space__left_paren__space_alertdefinition.resourceType.id_space__equal__space__colon_alertTemplateResourceTypeId_space__newline_AND_space_LOWER_left_paren__space_alertdefinition.name_space__right_paren__space_like_space__colon_name_space_ESCAPE_space__quote_\_quote__space__space__newline_AND_space_alertdefinition.deleted_space__equal__space__colon_deleted_space__right_paren__newline_] specified by [ResourceType[id=0, name=Query Cache, plugin=JBossAS7, category=Service]] discovery component is longer than the maximum length (500).
    at org.rhq.core.pluginapi.inventory.DiscoveredResourceDetails.setResourceKey(DiscoveredResourceDetails.java:143)
    at org.rhq.core.pluginapi.inventory.DiscoveredResourceDetails.<init>(DiscoveredResourceDetails.java:95)
    at org.rhq.modules.plugins.jbossas7.SubsystemDiscovery.discoverResources(SubsystemDiscovery.java:158)
    at sun.reflect.GeneratedMethodAccessor60.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.rhq.core.pc.util.DiscoveryComponentProxyFactory$ComponentInvocationThread.call(DiscoveryComponentProxyFactory.java:305)