java.lang.Throwable: Using stale writer, possibly forgotten call to store, old owner Thread Thread[RepositoryUpdater.worker,1,system], new owner Thread Thread[Code Completion,1,system] .
   at org.netbeans.modules.parsing.lucene.LuceneIndex$DirCache$OwnerReference.assertNoModifiedWriter(LuceneIndex.java:1098)
   at org.netbeans.modules.parsing.lucene.LuceneIndex$DirCache.beginTx(LuceneIndex.java:810)
   at org.netbeans.modules.parsing.lucene.LuceneIndex.run(LuceneIndex.java:369)
   at org.netbeans.modules.java.source.usages.PersistentClassIndex$PIWriter.<init>(PersistentClassIndex.java:449)
   at org.netbeans.modules.java.source.usages.PersistentClassIndex.getSourceAnalyser(PersistentClassIndex.java:133)
   at org.netbeans.modules.java.source.indexing.JavaParsingContext.getSourceAnalyzer(JavaParsingContext.java:187)
   at org.netbeans.modules.java.source.indexing.JavaParsingContext.delete(JavaParsingContext.java:242)
   at org.netbeans.modules.java.source.indexing.JavaCustomIndexer.clear(JavaCustomIndexer.java:511)
   at org.netbeans.modules.java.source.indexing.JavaCustomIndexer.index(JavaCustomIndexer.java:224)
   at org.netbeans.modules.parsing.spi.indexing.Indexable$MyAccessor$2.run(Indexable.java:158)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater.runIndexer(RepositoryUpdater.java:259)
   at org.netbeans.modules.parsing.spi.indexing.Indexable$MyAccessor.index(Indexable.java:156)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.doIndex(RepositoryUpdater.java:2474)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.access$1500(RepositoryUpdater.java:2074)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work$2.run(RepositoryUpdater.java:2381)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work$2.run(RepositoryUpdater.java:2379)
   at org.netbeans.modules.parsing.impl.indexing.errors.TaskCache.refreshTransaction(TaskCache.java:541)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.index(RepositoryUpdater.java:2379)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.scanFiles(RepositoryUpdater.java:2885)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$FileListWork.getDone(RepositoryUpdater.java:3238)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$Work.doTheWork(RepositoryUpdater.java:2979)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater$1.run(RepositoryUpdater.java:342)
   at org.netbeans.modules.parsing.impl.indexing.SuspendSupport.runWithNoSuspend(SuspendSupport.java:129)
   at org.netbeans.modules.parsing.impl.indexing.RepositoryUpdater.enforcedFileListUpdate(RepositoryUpdater.java:338)
   at org.netbeans.modules.parsing.spi.indexing.support.QuerySupport$1.call(QuerySupport.java:284)
   at org.netbeans.modules.parsing.spi.indexing.support.QuerySupport$1.call(QuerySupport.java:254)
   at org.netbeans.modules.masterfs.filebasedfs.utils.FileChangedManager.priorityIO(FileChangedManager.java:176)
   at org.netbeans.modules.masterfs.providers.ProvidedExtensions.priorityIO(ProvidedExtensions.java:360)
   at org.netbeans.modules.parsing.impl.Utilities.runPriorityIO(Utilities.java:72)
   at org.netbeans.modules.parsing.spi.indexing.support.QuerySupport.query(QuerySupport.java:254)
   at org.netbeans.modules.groovy.editor.api.GroovyIndex.search(GroovyIndex.java:626)
   at org.netbeans.modules.groovy.editor.api.GroovyIndex.getClasses(GroovyIndex.java:146)
   at org.netbeans.modules.groovy.editor.api.GroovyIndex.getClasses(GroovyIndex.java:100)
   at org.netbeans.modules.groovy.editor.api.completion.impl.TypesCompletion.complete(TypesCompletion.java:202)
   at org.netbeans.modules.groovy.editor.api.completion.impl.ProposalsCollector.completeTypes(ProposalsCollector.java:104)
   at org.netbeans.modules.groovy.editor.api.completion.CompletionHandler.complete(CompletionHandler.java:164)
   at org.netbeans.modules.csl.editor.completion.GsfCompletionProvider$JavaCompletionQuery.addCodeCompletionItems(GsfCompletionProvider.java:604)
   at org.netbeans.modules.csl.editor.completion.GsfCompletionProvider$JavaCompletionQuery.resolveCompletion(GsfCompletionProvider.java:591)
   at org.netbeans.modules.csl.editor.completion.GsfCompletionProvider$JavaCompletionQuery.access$400(GsfCompletionProvider.java:247)
   at org.netbeans.modules.csl.editor.completion.GsfCompletionProvider$JavaCompletionQuery$1.run(GsfCompletionProvider.java:331)
   at org.netbeans.modules.parsing.impl.TaskProcessor.callUserTask(TaskProcessor.java:583)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:150)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:134)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:200)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:197)
   at org.netbeans.modules.masterfs.filebasedfs.utils.FileChangedManager.priorityIO(FileChangedManager.java:176)
   at org.netbeans.modules.masterfs.providers.ProvidedExtensions.priorityIO(ProvidedExtensions.java:360)
   at org.netbeans.modules.parsing.impl.Utilities.runPriorityIO(Utilities.java:72)
   at org.netbeans.modules.parsing.impl.TaskProcessor.runUserTask(TaskProcessor.java:197)
   at org.netbeans.modules.parsing.api.ParserManager.parse(ParserManager.java:102)
   at org.netbeans.modules.csl.editor.completion.GsfCompletionProvider$JavaCompletionQuery.query(GsfCompletionProvider.java:340)
   at org.netbeans.spi.editor.completion.support.AsyncCompletionTask.run(AsyncCompletionTask.java:223)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1454)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2036)