org.jboss.tools.common.validation.JBTValidationException
	at org.jboss.tools.common.validation.ValidatorManager.validateInJob(ValidatorManager.java:101)
	at org.eclipse.wst.validation.internal.operations.ValidatorJob.run(ValidatorJob.java:78)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)
Caused by: java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:819)
	at java.util.ArrayList$Itr.next(ArrayList.java:791)
	at org.jboss.tools.jst.web.kb.internal.KbProject.getKBBuilderRequiredNatureDescriptions(KbProject.java:1001)
	at org.jboss.tools.jst.web.kb.internal.KbProject.checkKBBuilderInstalled(KbProject.java:1027)
	at org.jboss.tools.jsf.web.validation.JSFELValidationDelegate.shouldValidate(JSFELValidationDelegate.java:36)
	at org.jboss.tools.jst.web.kb.internal.validation.ELValidator.shouldValidate(ELValidator.java:646)
	at org.jboss.tools.jst.web.kb.internal.validation.ELValidator.shouldValidate(ELValidator.java:633)
	at org.jboss.tools.common.validation.ValidationContext.shouldValidate(ValidationContext.java:137)
	at org.jboss.tools.common.validation.ValidationContext.init(ValidationContext.java:126)
	at org.jboss.tools.common.validation.ValidationContext.<init>(ValidationContext.java:43)
	at org.jboss.tools.common.validation.ContextValidationHelper.getValidationContextManager(ContextValidationHelper.java:176)
	at org.jboss.tools.common.validation.ContextValidationHelper.getValidationContextManager(ContextValidationHelper.java:168)
	at org.jboss.tools.common.validation.ValidatorManager.validateInJob(ValidatorManager.java:65)
	... 2 more