java.lang.NullPointerException: The fo parameter cannot be null
   at org.openide.util.Parameters.notNull(Parameters.java:89)
   at org.openide.filesystems.FileUtil.isParentOf(FileUtil.java:1425)
   at org.netbeans.modules.maven.classpath.ClassPathProviderImpl.getType(ClassPathProviderImpl.java:207)
   at org.netbeans.modules.maven.classpath.ClassPathProviderImpl.findClassPath(ClassPathProviderImpl.java:148)
   at org.netbeans.modules.websvc.rest.support.SourceGroupSupport.getHandleClassName(SourceGroupSupport.java:273)
   at org.netbeans.modules.websvc.rest.support.SourceGroupSupport.getFileObjectFromClassName(SourceGroupSupport.java:295)
   at org.netbeans.modules.websvc.rest.nodes.OpenCookieFactory$OpenCookieImpl.doOpen(OpenCookieFactory.java:113)
   at org.netbeans.modules.websvc.rest.nodes.OpenCookieFactory$OpenCookieImpl.access$000(OpenCookieFactory.java:81)
   at org.netbeans.modules.websvc.rest.nodes.OpenCookieFactory$OpenCookieImpl$1.run(OpenCookieFactory.java:99)
   at org.netbeans.modules.progress.ui.RunOffEDTImpl$1.run(RunOffEDTImpl.java:169)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1423)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2033)