Unknown how to reproduce but stack trace indicates unsafe access of member variables.

java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:806)
at java.util.HashMap$EntryIterator.next(HashMap.java:847)
at java.util.HashMap$EntryIterator.next(HashMap.java:845)
at java.util.HashMap.putAllForCreate(HashMap.java:451)
at java.util.HashMap.clone(HashMap.java:682)
at org.jboss.ide.eclipse.archives.core.model.internal.ArchiveNodeDeltaImpl.loadDelta(ArchiveNodeDeltaImpl.java:215)
at org.jboss.ide.eclipse.archives.core.model.internal.ArchiveNodeDeltaImpl.getDelta(ArchiveNodeDeltaImpl.java:200)
at org.jboss.ide.eclipse.archives.core.model.internal.ArchiveNodeDeltaImpl.loadAllAffectedChildren(ArchiveNodeDeltaImpl.java:150)