java.lang.NoClassDefFoundError: org/netbeans/spi/server/ServerInstance
        at java.lang.ClassLoader.defineClass1(ClassLoader.java:0)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
        at org.netbeans.JarClassLoader.doLoadClass(JarClassLoader.java:254)
        at org.netbeans.ProxyClassLoader.selfLoadClass(ProxyClassLoader.java:245)
        at org.netbeans.ProxyClassLoader.loadClass(ProxyClassLoader.java:219)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
        at org.netbeans.modules.j2ee.deployment.impl.bridge.BridgingServerInstanceProvider.refreshCache(BridgingServerInstanceProvider.java:143)
        at org.netbeans.modules.j2ee.deployment.impl.bridge.BridgingServerInstanceProvider.getInstances(BridgingServerInstanceProvider.java:106)
        at org.netbeans.modules.server.ui.node.RootNode$ChildFactory.createKeys(RootNode.java:141)
        at org.openide.nodes.AsynchChildren.run(AsynchChildren.java:142)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:561)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:986)