Description of problem:

Platform BZ for https://issues.jboss.org/browse/GTNPORTAL-2571

Steps to Reproduce:

- Login as root
- Go to dashboard
- Keep pressing F5 for 10 seconds

Actual results:

09:02:47,951 ERROR [PortletApplicationController] Error while rendering the porlet
org.exoplatform.groovyscript.TemplateRuntimeException: Groovy template exception at DataText[pos=Position[col=1,line=11],data=          uicomponent.renderChild(UIDashboard.class);] for template app:/groovy/dashboard/webui/component/UIDashboardPortlet.gtmpl
    at org.exoplatform.groovyscript.GroovyScript.buildRuntimeException(GroovyScript.java:178)
...
Caused by: java.util.ConcurrentModificationException
    at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
    at java.util.AbstractList$Itr.next(AbstractList.java:343)
    at UIColumnContainer.run(UIColumnContainer.gtmpl:7)
    at org.exoplatform.groovyscript.GroovyScript.render(GroovyScript.java:111)
    at org.exoplatform.groovyscript.GroovyTemplate.render(GroovyTemplate.java:118)
    at org.exoplatform.groovyscript.text.TemplateService.merge(TemplateService.java:117)

As this keeps reloading, finally it will render a correct page so not a problem from user perspective.

Expected results:

No Exception