The following problem was reported via the automated error reporting:

Message: Problems occurred when invoking code from plug-in: "org.eclipse.core.resources".
java.util.ConcurrentModificationException: null
at java.util.HashMap$HashIterator.nextNode(HashMap.java:1437)
at java.util.HashMap$KeyIterator.next(HashMap.java:1461)
at org.jboss.tools.arquillian.core.internal.builder.ArquillianBuilder$1.visit(ArquillianBuilder.java:173)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:64)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:75)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:75)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:75)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:75)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:75)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:75)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:75)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:75)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:75)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:75)
at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:48)
at org.jboss.tools.arquillian.core.internal.builder.ArquillianBuilder.buildDelta(ArquillianBuilder.java:128)
at org.jboss.tools.arquillian.core.internal.builder.ArquillianBuilder.build(ArquillianBuilder.java:112)
at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:735)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:206)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:246)
at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:301)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:304)
at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:360)
at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:383)
at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:144)
at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:235)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)

Bundles:

Operating Systems:

The above information is a snapshot of the collected data. Visit https://aer.ctrlflow.com/redhat/reviewers/#!/problems/580cd1e9e4b081752d6bc9bf for the latest data.

Thank you for your assistance.
Your friendly error-reports-inbox.