Weird error on shutdown...

[jwcarman]

I don't think I've seen this on our server before, but I got this
today (we're 1.4-m2, since I haven't had time to upgrade us to m3):

java.lang.NoClassDefFoundError: org/apache/wicket/util/lang/PropertyResolver
        at org.apache.wicket.Application.internalDestroy(Application.java:905)
        at org.apache.wicket.protocol.http.WebApplication.internalDestroy(WebApplication.java:476)
        at org.apache.wicket.protocol.http.WicketFilter.destroy(WicketFilter.java:143)
        at org.apache.catalina.core.ApplicationFilterConfig.release(ApplicationFilterConfig.java:253)
        at org.apache.catalina.core.StandardContext.filterStop(StandardContext.java:3670)
        at org.apache.catalina.core.StandardContext.stop(StandardContext.java:4354)
        at org.apache.catalina.core.ContainerBase.removeChild(ContainerBase.java:893)
        at org.apache.catalina.startup.HostConfig.undeployApps(HostConfig.java:1180)
        at org.apache.catalina.startup.HostConfig.stop(HostConfig.java:1151)
        at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:313)
        at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:120)
        at org.apache.catalina.core.ContainerBase.stop(ContainerBase.java:1055)
        at org.apache.catalina.core.ContainerBase.stop(ContainerBase.java:1067)
        at org.apache.catalina.core.StandardEngine.stop(StandardEngine.java:448)
        at org.apache.catalina.core.StandardService.stop(StandardService.java:510)
        at org.apache.catalina.core.StandardServer.stop(StandardServer.java:734)
        at org.apache.catalina.startup.Catalina.stop(Catalina.java:602)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:577)
        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:585)
        at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:295)
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:433)

[liny]

My environment:
. Apache Tomcat/6.0.18
. JDK 1.6.0_12-b04

I got this weird message in tomcat log, too:

Nov 4, 2009 12:13:03 AM org.apache.catalina.startup.HostConfig checkResources
INFO: Reloading context [/acm]
Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase stop
INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/acm].[AppServlet] has not been started
Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase stop
INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/acm].[jsp] has not been started
Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase stop
INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/acm].[default] has not been started
Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor processChildren
SEVERE: Exception invoking periodic operation:
java.lang.NoClassDefFoundError: org/apache/wicket/util/lang/PropertyResolver
        at org.apache.wicket.Application.internalDestroy(Application.java:887)
        at org.apache.wicket.protocol.http.WebApplication.internalDestroy(WebApplication.java:448)
        at org.apache.wicket.protocol.http.WicketFilter.destroy(WicketFilter.java:143)
        at org.apache.catalina.core.ApplicationFilterConfig.release(ApplicationFilterConfig.java:332)
        at org.apache.catalina.core.StandardContext.filterStop(StandardContext.java:3744)
        at org.apache.catalina.core.StandardContext.stop(StandardContext.java:4513)
        at org.apache.catalina.startup.HostConfig.checkResources(HostConfig.java:1108)
        at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1214)
        at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:293)
        at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
        at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1337)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1601)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1610)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1590)
        at java.lang.Thread.run(Thread.java:619)
Nov 4, 2009 12:13:03 AM org.apache.catalina.core.StandardContext reload
INFO: Reloading this Context has started
Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase stop
INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/acm].[AppServlet] has not been started
Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase stop
INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/acm].[jsp] has not been started
Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase stop
INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/acm].[default] has not been started
Nov 4, 2009 12:13:03 AM org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor processChildren
SEVERE: Exception invoking periodic operation:
java.lang.NoClassDefFoundError: org/apache/wicket/util/lang/PropertyResolver
        at org.apache.wicket.Application.internalDestroy(Application.java:887)
        at org.apache.wicket.protocol.http.WebApplication.internalDestroy(WebApplication.java:448)
        at org.apache.wicket.protocol.http.WicketFilter.destroy(WicketFilter.java:143)
        at org.apache.catalina.core.ApplicationFilterConfig.release(ApplicationFilterConfig.java:332)
        at org.apache.catalina.core.StandardContext.filterStop(StandardContext.java:3744)
        at org.apache.catalina.core.StandardContext.stop(StandardContext.java:4513)
        at org.apache.catalina.core.StandardContext.reload(StandardContext.java:3093)
        at org.apache.catalina.loader.WebappLoader.backgroundProcess(WebappLoader.java:404)
        at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1309)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1601)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1610)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1610)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1590)
        at java.lang.Thread.run(Thread.java:619)

I checked wicket jar file, and org/apache/wicket/util/lang/PropertyResolver class does exist.
Is it tomcat bug or wicket bug?