project_key: JBEPP

After the portlet si redeployed few times (i.e. during the development), it cause the "This portlet encountered an error and could not be displayed" error after a while.

excerpt from the server.log is:
10:55:33,204 ERROR [LifeCycle] Cannot start object
org.gatein.pc.portlet.container.PortletInitializationException: Portlet class not found org.gatein.examples.HelloPortlet
	at org.gatein.pc.portlet.impl.jsr168.PortletContainerImpl.start(PortletContainerImpl.java:277)
	at org.gatein.pc.portlet.impl.container.PortletContainerLifeCycle.invokeStart(PortletContainerLifeCycle.java:76)
	at org.gatein.pc.portlet.impl.container.LifeCycle.managedStart(LifeCycle.java:93)
	at org.gatein.pc.portlet.impl.container.PortletApplicationLifeCycle.startDependents(PortletApplicationLifeCycle.java:351)

You can use attached "hello world" portlet to reproduce the issue.
1. build and copy the portlet into deply directory
2. import applications in application registry
3. put in on the "Home" page
4. change something in the code (i.e. add some stdout), rebuild and redeploy the portlet
5. click on the "SiteMap" and "Home" again
6. repeat 4. and 5. until error (usually three times is enough)