java.lang.NullPointerException
   at org.netbeans.modules.apisupport.project.ui.UnitTestLibrariesNode$LibrariesChildren$1.run(UnitTestLibrariesNode.java:228)
   at org.openide.util.Mutex.readAccess(Mutex.java:330)
   at org.netbeans.modules.apisupport.project.ui.UnitTestLibrariesNode$LibrariesChildren.refreshKeys(UnitTestLibrariesNode.java:224)
   at org.netbeans.modules.apisupport.project.ui.UnitTestLibrariesNode$LibrariesChildren.access$600(UnitTestLibrariesNode.java:193)
   at org.netbeans.modules.apisupport.project.ui.UnitTestLibrariesNode$LibrariesChildren$2.run(UnitTestLibrariesNode.java:278)
   at org.netbeans.modules.apisupport.project.ui.UnitTestLibrariesNode$LibrariesChildren.configurationXmlChanged(UnitTestLibrariesNode.java:288)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$3.run(AntProjectHelper.java:500)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$3.run(AntProjectHelper.java:495)
   at org.openide.util.Mutex.readAccess(Mutex.java:288)
   at org.netbeans.spi.project.support.ant.AntProjectHelper.fireChange(AntProjectHelper.java:495)
   at org.netbeans.spi.project.support.ant.AntProjectHelper.access$1500(AntProjectHelper.java:108)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$ActionImpl.run(AntProjectHelper.java:1332)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$ActionImpl.run(AntProjectHelper.java:1321)
   at org.openide.util.Mutex.readAccess(Mutex.java:288)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$RunnableImpl.run(AntProjectHelper.java:1317)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1418)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1960)