java.util.ConcurrentModificationException
        at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793)
        at java.util.HashMap$ValueIterator.next(HashMap.java:822)
        at java.util.AbstractCollection.addAll(AbstractCollection.java:305)
        at java.util.HashSet.<init>(HashSet.java:100)
        at org.netbeans.modules.apisupport.project.universe.ModuleList.getAllEntriesSoft(ModuleList.java:1142)
        at org.netbeans.modules.apisupport.project.universe.NbPlatform.getSourceLocationOfModule(NbPlatform.java:723)
        at org.netbeans.modules.apisupport.project.universe.BinaryEntry.getSourceLocation(BinaryEntry.java:111)
        at org.netbeans.modules.apisupport.project.queries.UpdateTrackingFileOwnerQuery.getOwner(UpdateTrackingFileOwnerQuery.java:92)
        at org.netbeans.modules.apisupport.project.queries.UpdateTrackingFileOwnerQuery.getOwner(UpdateTrackingFileOwnerQuery.java:72)
        at org.netbeans.api.project.FileOwnerQuery.getOwner(FileOwnerQuery.java:147)
        at org.netbeans.modules.java.project.JavadocForBinaryQueryImpl.findJavadoc(JavadocForBinaryQueryImpl.java:67)
        at org.netbeans.api.java.queries.JavadocForBinaryQuery.findJavadoc(JavadocForBinaryQuery.java:85)
        at org.netbeans.modules.apisupport.project.queries.GlobalJavadocForBinaryImpl.findForBinaryRoot(GlobalJavadocForBinaryImpl.java:99)
        at org.netbeans.modules.apisupport.project.queries.GlobalJavadocForBinaryImpl.findJavadoc(GlobalJavadocForBinaryImpl.java:76)
        at org.netbeans.api.java.queries.JavadocForBinaryQuery.findJavadoc(JavadocForBinaryQuery.java:85)
        at org.netbeans.modules.javadoc.search.JavadocRegistry.readRoots(JavadocRegistry.java:172)
        at org.netbeans.modules.javadoc.search.JavadocRegistry.getDocRoots(JavadocRegistry.java:127)
        at org.netbeans.modules.javadoc.search.IndexBuilder.refreshIndex(IndexBuilder.java:194)
        at org.netbeans.modules.javadoc.search.IndexBuilder.run(IndexBuilder.java:122)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:561)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:986)