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.EventControl.invokeDispatchers(EventControl.java:213)
   at org.openide.filesystems.EventControl.exitAtomicAction(EventControl.java:188)
   at org.openide.filesystems.EventControl.runAtomicAction(EventControl.java:129)
   at org.openide.filesystems.FileSystem.runAtomicAction(FileSystem.java:607)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.FileObjectFactory.refresh(FileObjectFactory.java:722)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.RootObj.invokeRefreshFor(RootObj.java:197)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.RootObj.invokeRefreshFor(RootObj.java:145)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.RootObj.setAttribute(RootObj.java:138)
   at org.openide.filesystems.FileUtil.refreshFor(FileUtil.java:172)
   at org.openide.filesystems.FileUtil$1.run(FileUtil.java:195)
Caused: org.openide.util.RequestProcessor$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.openide.filesystems.FileUtil.refreshAll(FileUtil.java:210)
   at org.apache.tools.ant.module.bridge.impl.BridgeImpl$1.run(BridgeImpl.java:320)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1452)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2032)