RS: multithread issue with the language detection

stack of 1.cause::java.util.ConcurrentModificationException: null
-> at java.util.HashMap$HashIterator.nextNode(HashMap.java:1442)
   at java.util.HashMap$ValueIterator.next(HashMap.java:1471)
   at org.olat.core.commons.services.text.impl.nutch.NGramProfile.normalize(NGramProfile.java:225)
   at org.olat.core.commons.services.text.impl.nutch.NGramProfile.analyze(NGramProfile.java:199)
   at org.olat.core.commons.services.text.impl.nutch.LanguageIdentifier.identify(LanguageIdentifier.java:175)
   at org.olat.core.commons.services.text.impl.nutch.LanguageIdentifier.identify(LanguageIdentifier.java:155)
   at org.olat.core.commons.services.text.impl.TextServiceImpl.detectLocale(TextServiceImpl.java:65)
   at org.olat.modules.fo.manager.ForumManager.updateCounters(ForumManager.java:1324)
   at org.olat.modules.fo.manager.ForumManager.saveMessage(ForumManager.java:817)
   at org.olat.modules.fo.manager.ForumManager.replyToMessage(ForumManager.java:788)
   at org.olat.modules.fo.ui.MessageEditController.commitMessage(MessageEditController.java:531)