java.lang.IllegalArgumentException: Duplicate in children list: META-INF/MANIFEST.MF
Children: [AbstractFileObject@1ab0354f[META-INF/MANIFEST.MF], AbstractFileObject@1ab0354f[META-INF/MANIFEST.MF], AbstractFileObject@7203103c[META-INF/maven]]
   at org.openide.filesystems.Ordering.getOrder(Ordering.java:101)
   at org.openide.filesystems.FileUtil.getOrder(FileUtil.java:2118)
   at org.openide.loaders.FolderChildren$1R.getPositionedFolderChildrenPairs(FolderChildren.java:213)
   at org.openide.loaders.FolderChildren$1R.run(FolderChildren.java:198)
Caused: org.openide.util.RequestProcessor$SlowItem: task failed due to: java.lang.IllegalArgumentException: Duplicate in children list: META-INF/MANIFEST.MF
Children: [AbstractFileObject@1ab0354f[META-INF/MANIFEST.MF], AbstractFileObject@1ab0354f[META-INF/MANIFEST.MF], AbstractFileObject@7203103c[META-INF/maven]]
   at org.openide.util.RequestProcessor.post(RequestProcessor.java:420)
   at org.openide.loaders.FolderChildren.refreshChildren(FolderChildren.java:233)
   at org.openide.loaders.FolderChildren.propertyChange(FolderChildren.java:145)
   at org.openide.util.WeakListenerImpl$PropertyChange.propertyChange(WeakListenerImpl.java:215)
   at java.beans.PropertyChangeSupport.fire(PropertyChangeSupport.java:335)
   at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:327)
   at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:263)
   at org.openide.loaders.FolderList.refresh(FolderList.java:349)
   at org.openide.loaders.FolderList.changedDataSystem(FolderList.java:247)
   at org.openide.loaders.DataObjectPool$Validator.refreshFolderOf(DataObjectPool.java:1158)
   at org.openide.loaders.DataObjectPool.deregister(DataObjectPool.java:862)
   at org.openide.loaders.DataObjectPool.access$900(DataObjectPool.java:60)
   at org.openide.loaders.DataObjectPool$Item.deregister(DataObjectPool.java:1000)
   at org.openide.loaders.DataObject.dispose(DataObject.java:230)
   at org.openide.loaders.DataObject.markInvalid0(DataObject.java:273)
   at org.openide.loaders.MultiDataObject.notifyFileDeleted(MultiDataObject.java:1442)
   at org.openide.loaders.DataObjectPool$FSListener.fileDeleted(DataObjectPool.java:652)
   at org.openide.filesystems.FCLSupport$DispatchEventWrapper.dispatchEventImpl(FCLSupport.java:181)
   at org.openide.filesystems.FCLSupport$DispatchEventWrapperMulti.dispatchAllEventsSync(FCLSupport.java:248)
   at org.openide.filesystems.FCLSupport$DispatchEventWrapper.dispatchEvent(FCLSupport.java:137)
   at org.openide.filesystems.FCLSupport.dispatchEvent(FCLSupport.java:112)
   at org.openide.filesystems.FileObject$ED.dispatch(FileObject.java:1425)
   at org.openide.filesystems.EventControl.invokeDispatchers(EventControl.java:213)
   at org.openide.filesystems.EventControl.exitAtomicAction(EventControl.java:188)
   at org.openide.filesystems.EventControl.finishAtomicAction(EventControl.java:116)
   at org.openide.filesystems.FileSystem.finishAtomicAction(FileSystem.java:525)
   at org.openide.filesystems.JarFileSystem.parse(JarFileSystem.java:872)
   at org.openide.filesystems.JarFileSystem.access$100(JarFileSystem.java:93)
   at org.openide.filesystems.JarFileSystem$1.fileChanged(JarFileSystem.java:346)
   at sun.reflect.GeneratedMethodAccessor9.invoke(GeneratedMethodAccessor9.java:0)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.lang.reflect.Method.invoke(Method.java:497)
   at org.openide.util.WeakListenerImpl$ProxyListener.invoke(WeakListenerImpl.java:487)
   at com.sun.proxy.$Proxy1.fileChanged(.java:0)
   at org.openide.filesystems.FCLSupport$DispatchEventWrapper.dispatchEventImpl(FCLSupport.java:178)
   at org.openide.filesystems.FCLSupport$DispatchEventWrapperSingle.dispatchAllEventsSync(FCLSupport.java:224)
   at org.openide.filesystems.FCLSupport$DispatchEventWrapper.dispatchEvent(FCLSupport.java:137)
   at org.openide.filesystems.FCLSupport.dispatchEvent(FCLSupport.java:105)
   at org.openide.filesystems.FileObject$ED.dispatch(FileObject.java:1388)
   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:499)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.FileObjectFactory.refreshFor(FileObjectFactory.java:865)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.RootObj.invokeRefreshFor(RootObj.java:199)
   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:189)
   at org.netbeans.modules.maven.api.NbMavenProject.doFireReload(NbMavenProject.java:562)
   at org.netbeans.modules.maven.api.NbMavenProject.access$200(NbMavenProject.java:94)
   at org.netbeans.modules.maven.api.NbMavenProject$AccessorImpl.doFireReload(NbMavenProject.java:140)
   at org.netbeans.modules.maven.NbMavenProjectImpl$1.run(NbMavenProjectImpl.java:151)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1443)
   at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:68)
   at org.openide.util.lookup.Lookups.executeWith(Lookups.java:303)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2058)