How can I debug Cometd / Grails 1.2.1 problem?

Question

When I add the Cometd plugin to Grails 1.2.1, grail's "jetty" debug environment will no longer start up.

I have been unable to debug this, not being familiar enough with the underlying components. (This is a big issue with Grails development in general. While it tries to hide everything from you, pretty soon you have to become an expert with Hibernate, Java 1.6, jetty, etc, in order to debug grails problems)

To reproduce, start a grails 1.2.1 project, and install the cometd-grails plugin. When you do a run-app, you'll see:

Running Grails application..
2010-03-20 18:32:28,879 [main] ERROR context.ContextLoader  - Context initialization failed
org.springframework.beans.factory.access.BootstrapException: Error executing bootstraps; nested exception is org.codehaus.groovy.runtime.InvokerInvocationException: java.lang.NoClassDefFoundError: org/mortbay/util/ajax/JSON$Source
        at org.codehaus.groovy.grails.web.context.GrailsContextLoader.createWebApplicationContext(GrailsContextLoader.java:74)
        at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:192)
        at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47)
        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3961)
        at org.apache.catalina.core.StandardContext.start(StandardContext.java:4456)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
        at org.apache.catalina.core.StandardHost.start(StandardHost.java:722)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
        at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
        at org.apache.catalina.core.StandardService.start(StandardService.java:515)
        at org.apache.catalina.core.StandardServer.start(StandardServer.java:708)
        at org.apache.catalina.startup.Tomcat.start(Tomcat.java:286)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoCachedMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:229)
        at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:52)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:40)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:117)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:121)
        at org.grails.tomcat.TomcatServer.start(TomcatServer.groovy:135)
        at grails.web.container.EmbeddableServer$start.call(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:40)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:117)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:129)
        at _GrailsRun_groovy$_run_closure5_closure12.doCall(_GrailsRun_groovy:158)
        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.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoCachedMethodSite.invoke(PogoMetaMethodSite.java:225)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:51)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:44)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:143)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:151)
        at _GrailsRun_groovy$_run_closure5_closure12.doCall(_GrailsRun_groovy)
        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.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.Closure.call(Closure.java:279)
        at groovy.lang.Closure.call(Closure.java:274)
        at groovy.lang.Closure$call.call(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:40)
        at groovy.lang.Closure$call.call(Unknown Source)
        at _GrailsSettings_groovy$_run_closure10.doCall(_GrailsSettings_groovy:287)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoCachedMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSite.java:266)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:51)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:44)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:56)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:155)
        at _GrailsSettings_groovy$_run_closure10.call(_GrailsSettings_groovy)
        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.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.MetaClassImpl.invokePropertyOrMissing(MetaClassImpl.java:1095)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1051)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:706)
        at groovy.lang.GroovyObjectSupport.invokeMethod(GroovyObjectSupport.java:44)
        at groovy.lang.Script.invokeMethod(Script.java:78)
        at groovy.lang.MetaClassImpl.invokeMethodOnGroovyObject(MetaClassImpl.java:1114)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1011)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:66)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:44)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:143)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:155)
        at _GrailsRun_groovy$_run_closure5.doCall(_GrailsRun_groovy:149)
        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.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoCachedMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSite.java:266)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:51)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:44)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:143)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:151)
        at _GrailsRun_groovy$_run_closure5.call(_GrailsRun_groovy)
        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.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.MetaClassImpl.invokePropertyOrMissing(MetaClassImpl.java:1095)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1051)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:66)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:44)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:143)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:151)
        at _GrailsRun_groovy.runInline(_GrailsRun_groovy:115)
        at _GrailsRun_groovy.this$4$runInline(_GrailsRun_groovy)
        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.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:997)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.DelegatingMetaClass.invokeMethod(DelegatingMetaClass.java:149)
        at org.codehaus.gant.GantMetaClass.invokeMethod(GantMetaClass.java:127)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:66)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:44)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:143)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:163)
        at _GrailsRun_groovy$_run_closure1.doCall(_GrailsRun_groovy:59)
        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.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.DelegatingMetaClass.invokeMethod(DelegatingMetaClass.java:149)
        at org.codehaus.gant.GantMetaClass.invokeMethod(GantMetaClass.java:127)
        at groovy.lang.Closure.call(Closure.java:279)
        at groovy.lang.Closure.call(Closure.java:292)
        at sun.reflect.GeneratedMethodAccessor63.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.DelegatingMetaClass.invokeMethod(DelegatingMetaClass.java:149)
        at org.codehaus.gant.GantMetaClass.invokeMethod(GantMetaClass.java:127)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:39)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:40)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:54)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)
        at org.codehaus.gant.GantBinding$_initializeGantBinding_closure4_closure8_closure9.doCall(GantBinding.groovy:152)
        at sun.reflect.GeneratedMethodAccessor77.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoCachedMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSite.java:266)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:51)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:151)
        at org.codehaus.gant.GantBinding$_initializeGantBinding_closure4_closure8_closure9.doCall(GantBinding.groovy)
        at sun.reflect.GeneratedMethodAccessor76.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.Closure.call(Closure.java:279)
        at groovy.lang.Closure.call(Closure.java:274)
        at groovy.lang.Closure$call.call(Unknown Source)
        at org.codehaus.gant.GantBinding.withTargetEvent(GantBinding.groovy:90)
        at org.codehaus.gant.GantBinding.this$4$withTargetEvent(GantBinding.groovy)
        at sun.reflect.GeneratedMethodAccessor70.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:997)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:706)
        at groovy.lang.GroovyObjectSupport.invokeMethod(GroovyObjectSupport.java:44)
        at groovy.lang.MetaClassImpl.invokeMethodOnGroovyObject(MetaClassImpl.java:1114)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1011)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:66)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:159)
        at org.codehaus.gant.GantBinding$_initializeGantBinding_closure4_closure8.doCall(GantBinding.groovy:152)
        at sun.reflect.GeneratedMethodAccessor69.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoCachedMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSite.java:266)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:51)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:151)
        at org.codehaus.gant.GantBinding$_initializeGantBinding_closure4_closure8.doCall(GantBinding.groovy)
        at sun.reflect.GeneratedMethodAccessor68.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.Closure.call(Closure.java:279)
        at groovy.lang.Closure.call(Closure.java:274)
        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.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.MetaClassImpl.invokePropertyOrMissing(MetaClassImpl.java:1095)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1051)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:706)
        at groovy.lang.GroovyObjectSupport.invokeMethod(GroovyObjectSupport.java:44)
        at groovy.lang.Script.invokeMethod(Script.java:78)
        at groovy.lang.MetaClassImpl.invokeMethodOnGroovyObject(MetaClassImpl.java:1114)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1011)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.DelegatingMetaClass.invokeMethod(DelegatingMetaClass.java:149)
        at org.codehaus.gant.GantMetaClass.invokeMethod(GantMetaClass.java:127)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:66)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:44)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:143)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:147)
        at RunApp$_run_closure1.doCall(RunApp.groovy:33)
        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.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.DelegatingMetaClass.invokeMethod(DelegatingMetaClass.java:149)
        at org.codehaus.gant.GantMetaClass.invokeMethod(GantMetaClass.java:127)
        at groovy.lang.Closure.call(Closure.java:279)
        at groovy.lang.Closure.call(Closure.java:292)
        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.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.DelegatingMetaClass.invokeMethod(DelegatingMetaClass.java:149)
        at org.codehaus.gant.GantMetaClass.invokeMethod(GantMetaClass.java:127)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:39)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:40)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:54)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)
        at org.codehaus.gant.GantBinding$_initializeGantBinding_closure4_closure8_closure9.doCall(GantBinding.groovy:152)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoCachedMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSite.java:266)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:51)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:151)
        at org.codehaus.gant.GantBinding$_initializeGantBinding_closure4_closure8_closure9.doCall(GantBinding.groovy)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.Closure.call(Closure.java:279)
        at groovy.lang.Closure.call(Closure.java:274)
        at groovy.lang.Closure$call.call(Unknown Source)
        at org.codehaus.gant.GantBinding.withTargetEvent(GantBinding.groovy:90)
        at org.codehaus.gant.GantBinding.this$4$withTargetEvent(GantBinding.groovy)
        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.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:86)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:234)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1049)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:997)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:706)
        at groovy.lang.GroovyObjectSupport.invokeMethod(GroovyObjectSupport.java:44)
        at groovy.lang.MetaClassImpl.invokeMethodOnGroovyObject(MetaClassImpl.java:1114)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1011)
        at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:923)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:880)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:66)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:159)
        at org.codehaus.gant.GantBinding$_initializeGantBinding_closure4_closure8.doCall(GantBinding.groovy:152)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoCachedMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSite.java:266)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:51)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:151)
        at org.codehaus.gant.GantBinding$_initializeGantBinding_closure4_closure8.doCall(GantBinding.groovy)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native

Answer 1

I just figured it out. I needed to add

jetty-util-6.1.14.jar 

in my lib directory. Strictly speaking, I didn't figure it out; I was able to find a reference in a bug report that suggested this. The connection between this message

java.lang.NoClassDefFoundError: org/mortbay/util/ajax/JSON$Source

and figuring out that that means I need jetty-util is hard for me to determine, if I wasn't fortunate enough to find it after several hours of googling....