failed HelloWorldApplication
javax.servlet.ServletException: wicket.WicketRuntimeException: Unable to create application of class foobar.HelloWorldApplication
        at org.mortbay.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:437)
        at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:256)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
        at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:617)
        at org.mortbay.jetty.servlet.Context.startContext(Context.java:139)
        at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1218)
        at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:500)
        at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:448)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
        at org.mortbay.jetty.handler.HandlerCollection.doStart(HandlerCollection.java:147)
        at org.mortbay.jetty.handler.ContextHandlerCollection.doStart(ContextHandlerCollection.java:161)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
        at org.mortbay.jetty.handler.HandlerCollection.doStart(HandlerCollection.java:147)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
        at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:117)
        at org.mortbay.jetty.Server.doStart(Server.java:220)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
        at org.mortbay.xml.XmlConfiguration.main(XmlConfiguration.java:947)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.mortbay.start.Main.invokeMain(Main.java:183)
        at org.mortbay.start.Main.start(Main.java:497)
        at org.mortbay.start.Main.main(Main.java:115)
Caused by: wicket.WicketRuntimeException: Unable to create application of class foobar.HelloWorldApplication
        at wicket.protocol.http.ContextParamWebApplicationFactory.createApplication(ContextParamWebApplicationFactory.java:68)
        at wicket.protocol.http.WicketServlet.init(WicketServlet.java:275)
        at javax.servlet.GenericServlet.init(GenericServlet.java:241)
        at org.mortbay.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:433)
        ... 24 more
Caused by: java.lang.ClassNotFoundException: foobar.HelloWorldApplication
        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)