java.lang.NoClassDefFoundError: org/openide/util/Enumerations$RNulls
   at org.openide.util.Enumerations.removeNulls(Enumerations.java:161)
   at org.openide.filesystems.AbstractFileSystem.existingFileObjects(AbstractFileSystem.java:410)
   at org.openide.filesystems.AbstractFileSystem.existingFileObjects(AbstractFileSystem.java:385)
   at org.openide.filesystems.JarFileSystem$1.fileDeleted(JarFileSystem.java:377)
   at sun.reflect.GeneratedMethodAccessor176.invoke(GeneratedMethodAccessor176.java:0)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.lang.reflect.Method.invoke(Method.java:601)
   at org.openide.util.WeakListenerImpl$ProxyListener.invoke(WeakListenerImpl.java:457)
   at $Proxy1.fileDeleted(.java:0)
   at org.openide.filesystems.FCLSupport$DispatchEventWrapper.dispatchEventImpl(FCLSupport.java:148)
   at org.openide.filesystems.FCLSupport$DispatchEventWrapper.dispatchEvent(FCLSupport.java:128)
   at org.openide.filesystems.FCLSupport.dispatchEvent(FCLSupport.java:105)
   at org.openide.filesystems.FileObject$ED.dispatch(FileObject.java:1242)
   at org.openide.filesystems.FileSystem$EventDispatcher.run(FileSystem.java:997)
   at org.openide.filesystems.EventControl.dispatchEvent(EventControl.java:84)
   at org.openide.filesystems.FileSystem.dispatchEvent(FileSystem.java:642)
   at org.openide.filesystems.FileObject.dispatchEvent(FileObject.java:564)
   at org.openide.filesystems.FileObject.fireFileDeletedEvent(FileObject.java:540)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.BaseFileObj.fireFileDeletedEvent(BaseFileObj.java:696)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.FolderObj.refreshImpl(FolderObj.java:510)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.FolderObj.refreshImpl(FolderObj.java:506)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.FolderObj.refreshImpl(FolderObj.java:506)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.FolderObj.refreshImpl(FolderObj.java:506)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.BaseFileObj.refresh(BaseFileObj.java:818)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.FolderObj.refresh(FolderObj.java:553)
   at org.openide.filesystems.FileObject.refresh(FileObject.java:1130)
   at org.netbeans.modules.masterfs.watcher.Watcher$1.run(Watcher.java:373)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1452)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2032)
Caused: org.openide.util.RequestProcessor$SlowItem: task failed due to: java.lang.NoClassDefFoundError: org/openide/util/Enumerations$RNulls
   at org.openide.util.RequestProcessor$Task.schedule(RequestProcessor.java:1493)
   at org.netbeans.modules.masterfs.watcher.Watcher.enqueue(Watcher.java:386)
   at org.netbeans.modules.masterfs.watcher.Watcher.access$200(Watcher.java:74)
   at org.netbeans.modules.masterfs.watcher.Watcher$Ext.run(Watcher.java:323)
   at java.lang.Thread.run(Thread.java:722)