java.lang.IllegalStateException
   at org.openide.util.Mutex.enterImpl(Mutex.java:654)
   at org.openide.util.Mutex.enter(Mutex.java:634)
   at org.openide.util.Mutex.writeEnter(Mutex.java:612)
   at org.openide.util.Mutex$Privileged.enterWriteAccess(Mutex.java:1665)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.FolderObj.refreshImpl(FolderObj.java:460)
   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)