java.util.ConcurrentModificationException
        at java.util.Hashtable$Enumerator.next(Hashtable.java:1020)
        at org.openide.util.NbCollections.checkedMapByCopy(NbCollections.java:148)
        at org.netbeans.modules.apisupport.project.universe.ModuleList.parseProperties(ModuleList.java:751)
        at org.netbeans.modules.apisupport.project.universe.ModuleList.scanPossibleProject(ModuleList.java:322)
        at org.netbeans.modules.apisupport.project.universe.ModuleList.scanNetBeansOrgStableSources(ModuleList.java:268)
        at org.netbeans.modules.apisupport.project.universe.ModuleList.createModuleListFromNetBeansOrgSources(ModuleList.java:236)
        at org.netbeans.modules.apisupport.project.universe.ModuleList.findOrCreateModuleListFromNetBeansOrgSources(ModuleList.java:226)
        at org.netbeans.modules.apisupport.project.universe.ModuleList$1.run(ModuleList.java:173)
        at org.netbeans.modules.apisupport.project.universe.ModuleList$1.run(ModuleList.java:144)
        at org.openide.util.Mutex.readAccess(Mutex.java:291)
        at org.netbeans.modules.apisupport.project.universe.ModuleList.getModuleList(ModuleList.java:143)
        at org.netbeans.modules.apisupport.project.NbModuleProject.getModuleList(NbModuleProject.java:511)
        at org.netbeans.modules.apisupport.project.Evaluator$2.run(Evaluator.java:225)
        at org.netbeans.modules.apisupport.project.Evaluator$2.run(Evaluator.java:220)
        at org.openide.util.Mutex.readAccess(Mutex.java:252)
        at org.netbeans.modules.apisupport.project.Evaluator.reset(Evaluator.java:219)
        at org.netbeans.modules.apisupport.project.Evaluator.access$100(Evaluator.java:96)
        at org.netbeans.modules.apisupport.project.Evaluator$1.run(Evaluator.java:207)
        at org.netbeans.modules.apisupport.project.Evaluator$1.run(Evaluator.java:204)
        at org.openide.util.Mutex.readAccess(Mutex.java:252)
        at org.netbeans.modules.apisupport.project.Evaluator.delegatingEvaluator(Evaluator.java:203)
        at org.netbeans.modules.apisupport.project.Evaluator.evaluate(Evaluator.java:162)
        at org.netbeans.modules.apisupport.project.queries.SourceForBinaryImpl.getModuleJarClusterPath(SourceForBinaryImpl.java:140)
        at org.netbeans.modules.apisupport.project.queries.SourceForBinaryImpl.findSourceRoots(SourceForBinaryImpl.java:84)
        at org.netbeans.modules.java.project.ProjectSourceForBinaryQuery.findSourceRoots(ProjectSourceForBinaryQuery.java:69)
        at org.netbeans.api.java.queries.SourceForBinaryQuery.findSourceRoots(SourceForBinaryQuery.java:89)
        at org.netbeans.modules.java.source.classpath.GlobalSourcePath.createResources(GlobalSourcePath.java:296)
        at org.netbeans.modules.java.source.classpath.GlobalSourcePath.access$2200(GlobalSourcePath.java:96)
        at org.netbeans.modules.java.source.classpath.GlobalSourcePath$SourcePathImplementation.getResources(GlobalSourcePath.java:589)
        at org.netbeans.api.java.classpath.ClassPath.entries(ClassPath.java:294)
        at org.netbeans.modules.java.source.usages.RepositoryUpdater$CompileWorker$1.run(RepositoryUpdater.java:1170)
        at org.netbeans.modules.java.source.usages.RepositoryUpdater$CompileWorker$1.run(RepositoryUpdater.java:1119)
        at org.netbeans.modules.java.source.usages.ClassIndexManager.writeLock(ClassIndexManager.java:100)
        at org.netbeans.modules.java.source.usages.RepositoryUpdater$CompileWorker.run(RepositoryUpdater.java:1116)
        at org.netbeans.modules.java.source.usages.RepositoryUpdater$CompileWorker.run(RepositoryUpdater.java:1089)
        at org.netbeans.api.java.source.JavaSource$CompilationJob.run(JavaSource.java:1439)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:417)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:269)
        at java.util.concurrent.FutureTask.run(FutureTask.java:123)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)
        at java.lang.Thread.run(Thread.java:595)