Description of problem:
This issue is reported in JBoss ON upgraded from 3.3.2 to 3.3.7. However, further testing showed that the same WARN message was logged in all 3.3 versions of JBoss ON. This error is logged whenever user navigate to JBoss ON UI dashboard - in case it has Recent Events portlet or when user navigate to the resource's Summary tab that contains Resource: Events portlet. This error does not affect collection of events. 

Version-Release number of selected component (if applicable):
JBoss ON 3.3.x

How reproducible:
Always

Steps to Reproduce:
1. Install JBoss ON;
2. Import EAP server into JBoss ON inventory;
3. Enable events collection for imported EAP server;
4. Make sure that either JBoss ON Dashboard contains Recent Events portlet or resource's Summary page contains Resource: Events portlet;
5. Start to collect events;
6. Navigate to JBoss ON UI Dashboard or to EAP's Summary page;

Actual results:
For every collected event in the portlet a WARN message "Could not initialize private org.rhq.core.domain.event.EventSource org.rhq.core.domain.event.Event.source" will be logged in the server.log file;

Expected results:
No WARN messages are logged;

Additional info:

The server.log in DEBUG mode shows the following:

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14:59:38,140 DEBUG [org.rhq.enterprise.server.util.CriteriaQueryGenerator] (http-0.0.0.0:7080-2) SELECT  new org.rhq.core.domain.event.composite.EventComposite(    event.detail,   event.source.resource.id,   event.source.resource.name,   event.source.resource.ancestry,   event.source.resource.resourceType.id,   event.id,   event.severity,   event.source.location,   event.timestamp ) 
FROM Event event
WHERE ( event.source.resourceId = :resourceId 
AND LOWER( event.source.location )  like :sourceName ESCAPE '\\'  )
ORDER BY event.timestamp DESC, event.id ASC

14:59:38,140 DEBUG [org.rhq.enterprise.server.util.CriteriaQueryGenerator] (http-0.0.0.0:7080-2) Bind: (resourceId, 10100)
14:59:38,140 DEBUG [org.rhq.enterprise.server.util.CriteriaQueryGenerator] (http-0.0.0.0:7080-2) Bind: (sourceName, %%)
14:59:38,141 DEBUG [org.rhq.enterprise.server.util.CriteriaQueryGenerator] (http-0.0.0.0:7080-2) SELECT COUNT(*)
FROM Event event
WHERE ( event.source.resourceId = :resourceId 
AND LOWER( event.source.location )  like :sourceName ESCAPE '\\'  )

14:59:38,141 DEBUG [org.rhq.enterprise.server.util.CriteriaQueryGenerator] (http-0.0.0.0:7080-2) Bind: (resourceId, 10100)
14:59:38,141 DEBUG [org.rhq.enterprise.server.util.CriteriaQueryGenerator] (http-0.0.0.0:7080-2) Bind: (sourceName, %%)
14:59:38,142 DEBUG [org.rhq.enterprise.server.util.CriteriaQueryRunner] (http-0.0.0.0:7080-2) Could not initialize private org.rhq.core.domain.event.EventSource org.rhq.core.domain.event.Event.source  Following exception has caused the problem: : java.lang.IllegalArgumentException: Can not set org.rhq.core.domain.event.EventSource field org.rhq.core.domain.event.Event.source to org.rhq.core.domain.event.composite.EventComposite
	...
	at org.rhq.enterprise.server.util.CriteriaQueryRunner.initialize(CriteriaQueryRunner.java:188) [rhq-server.jar:4.12.0.JON330GA-redhat-7]
	at org.rhq.enterprise.server.util.CriteriaQueryRunner.initJoinFetchFields(CriteriaQueryRunner.java:173) [rhq-server.jar:4.12.0.JON330GA-redhat-7]
	at org.rhq.enterprise.server.util.CriteriaQueryRunner.finalizeCollection(CriteriaQueryRunner.java:147) [rhq-server.jar:4.12.0.JON330GA-redhat-7]
	at org.rhq.enterprise.server.util.CriteriaQueryRunner.execute(CriteriaQueryRunner.java:96) [rhq-server.jar:4.12.0.JON330GA-redhat-7]
	at org.rhq.enterprise.server.event.EventManagerBean.findEventCompositesByCriteria(EventManagerBean.java:480) [rhq-server.jar:4.12.0.JON330GA-redhat-7]
	...
	at org.rhq.enterprise.server.common.PerformanceMonitorInterceptor.monitorHibernatePerformance(PerformanceMonitorInterceptor.java:26) [rhq-server.jar:4.12.0.JON330GA-redhat-7]
	...
	at org.rhq.enterprise.server.common.TransactionInterruptInterceptor.addCheckedActionToTransactionManager(TransactionInterruptInterceptor.java:78) [rhq-server.jar:4.12.0.JON330GA-redhat-7]
	...
	at org.rhq.enterprise.server.authz.RequiredPermissionsInterceptor.checkRequiredPermissions(RequiredPermissionsInterceptor.java:156) [rhq-server.jar:4.12.0.JON330GA-redhat-7]
	...
	at org.rhq.enterprise.server.event.EventManagerLocal$$$view112.findEventCompositesByCriteria(Unknown Source) [rhq-server.jar:4.12.0.JON330GA-redhat-7]
	at org.rhq.coregui.server.gwt.EventGWTServiceImpl.findEventCompositesByCriteria(EventGWTServiceImpl.java:109)
	...
	at org.rhq.helpers.rtfilter.filter.RtFilter.doFilter(RtFilter.java:125) [rhq-rtfilter-4.12.0.JON330GA-redhat-1.jar:4.12.0.JON330GA-redhat-1]
	...
	at org.rhq.coregui.server.filter.CacheControlFilter.doFilter(CacheControlFilter.java:71)
	...
14:59:38,145 DEBUG [org.rhq.enterprise.server.util.CriteriaQueryRunner] (http-0.0.0.0:7080-2) Could not nullify non-initialized field [private org.rhq.core.domain.event.EventSource org.rhq.core.domain.event.Event.source].: java.lang.IllegalArgumentException: Can not set org.rhq.core.domain.event.EventSource field org.rhq.core.domain.event.Event.source to org.rhq.core.domain.event.composite.EventComposite
	...

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