java.lang.AssertionError
        at org.netbeans.spi.project.support.ant.ProjectProperties$PP.write(ProjectProperties.java:216)
        at org.netbeans.spi.project.support.ant.ProjectProperties.write(ProjectProperties.java:133)
        at org.netbeans.spi.project.support.ant.AntProjectHelper.save(AntProjectHelper.java:572)
        at org.netbeans.spi.project.support.ant.AntProjectHelper.access$100(AntProjectHelper.java:92)
        at org.netbeans.spi.project.support.ant.AntProjectHelper$1.save(AntProjectHelper.java:130)
        at org.netbeans.modules.project.ant.AntBasedProjectFactorySingleton.saveProject(AntBasedProjectFactorySingleton.java:215)
        at org.netbeans.api.project.ProjectManager$7.run(ProjectManager.java:611)
        at org.netbeans.api.project.ProjectManager$7.run(ProjectManager.java:601)
        at org.openide.util.Mutex.writeAccess(Mutex.java:433)
        at org.openide.util.Mutex$1R.run(Mutex.java:1305)
        at org.openide.util.Mutex.doWrapperAccess(Mutex.java:1318)
        at org.openide.util.Mutex.writeAccess(Mutex.java:426)
        at org.netbeans.api.project.ProjectManager.saveProject(ProjectManager.java:600)
        at org.netbeans.modules.web.project.classpath.WebProjectLibrariesModifierImpl$1.run(WebProjectLibrariesModifierImpl.java:148)
        at org.netbeans.modules.web.project.classpath.WebProjectLibrariesModifierImpl$1.run(WebProjectLibrariesModifierImpl.java:122)
        at org.openide.util.Mutex.writeAccess(Mutex.java:433)
        at org.openide.util.Mutex$1R.run(Mutex.java:1305)
        at org.netbeans.api.project.ProjectManager$2$1.run(ProjectManager.java:120)
        at org.openide.filesystems.EventControl.runAtomicAction(EventControl.java:120)
        at org.openide.filesystems.FileSystem.runAtomicAction(FileSystem.java:499)
        at org.openide.filesystems.FileUtil.runAtomicAction(FileUtil.java:167)
        at org.netbeans.api.project.ProjectManager$2.execute(ProjectManager.java:118)
        at org.openide.util.Mutex.doWrapperAccess(Mutex.java:1320)
        at org.openide.util.Mutex.writeAccess(Mutex.java:426)
        at org.netbeans.modules.web.project.classpath.WebProjectLibrariesModifierImpl.handlePackageLibraryClassPathItems(WebProjectLibrariesModifierImpl.java:120)
        at org.netbeans.modules.web.project.classpath.WebProjectLibrariesModifierImpl.handlePackageLibraries(WebProjectLibrariesModifierImpl.java:111)
        at org.netbeans.modules.web.project.classpath.WebProjectLibrariesModifierImpl.addPackageLibraries(WebProjectLibrariesModifierImpl.java:96)
        at org.netbeans.modules.visualweb.project.jsf.api.JsfProjectUtils.addLibraryReferences(JsfProjectUtils.java:1513)
        at org.netbeans.modules.visualweb.project.jsf.libraries.JsfProjectLibrary.addLibrary(JsfProjectLibrary.java:144)
        at org.netbeans.modules.visualweb.project.jsf.framework.JsfProjectTemplate.addLibrary(JsfProjectTemplate.java:74)
        at org.netbeans.modules.visualweb.project.jsf.framework.JSFFrameworkProvider.extendImpl(JSFFrameworkProvider.java:194)
        at org.netbeans.modules.visualweb.project.jsf.framework.JSFConfigurationPanel.extend(JSFConfigurationPanel.java:115)
        at org.netbeans.modules.web.project.ui.wizards.NewWebProjectWizardIterator.instantiate(NewWebProjectWizardIterator.java:188)
        at org.openide.loaders.TemplateWizard$InstantiatingIteratorBridge.instantiate(TemplateWizard.java:1023)
        at org.openide.loaders.TemplateWizard.handleInstantiate(TemplateWizard.java:595)
        at org.openide.loaders.TemplateWizard.instantiateNewObjects(TemplateWizard.java:416)
        at org.openide.loaders.TemplateWizardIterImpl.instantiate(TemplateWizardIterImpl.java:253)
        at org.openide.loaders.TemplateWizardIteratorWrapper.instantiate(TemplateWizardIteratorWrapper.java:165)
        at org.openide.WizardDescriptor.callInstantiateOpen(WizardDescriptor.java:1384)
        at org.openide.WizardDescriptor.callInstantiate(WizardDescriptor.java:1341)
        at org.openide.WizardDescriptor.access$1600(WizardDescriptor.java:119)
        at org.openide.WizardDescriptor$Listener$2$1.run(WizardDescriptor.java:1908)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:561)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:986)