Exception in thread "Thread_10" java.util.ConcurrentModificationException
	at java.util.LinkedHashMap$LinkedHashIterator.nextEntry(LinkedHashMap.java:394)
	at java.util.LinkedHashMap$EntryIterator.next(LinkedHashMap.java:413)
	at java.util.LinkedHashMap$EntryIterator.next(LinkedHashMap.java:412)
	at org.basex.core.users.User.find(User.java:195)
	at org.basex.core.users.User.perm(User.java:183)
	at org.basex.core.users.User.has(User.java:231)
	at org.basex.core.Context.perm(Context.java:246)
	at org.basex.core.Command.execute(Command.java:85)
	at org.basex.api.client.LocalSession.execute(LocalSession.java:132)
	at org.basex.api.client.Session.execute(Session.java:36)
	at basextest.BaseXTest$Writer.store(BaseXTest.java:59)
	at basextest.BaseXTest$Writer.run(BaseXTest.java:86)
	at java.lang.Thread.run(Thread.java:745)