Closure.memoize fails on Google App Engine

cl = {a, b ->
    sleep(3000) // simulate some time consuming processing
    a + b
}
mem = cl.memoize()

def callClosure(a, b) {
    def start = System.currentTimeMillis()

    mem(a, b)

    println "Inputs(a = $a, b = $b) - took ${System.currentTimeMillis() - start} msecs."
}

callClosure(1, 2)
callClosure(1, 2)
callClosure(2, 3)
callClosure(2, 3)
callClosure(3, 4)
callClosure(3, 4)

callClosure(1, 2)
callClosure(2, 3)
callClosure(3, 4)

java.security.AccessControlException: access denied (java.lang.RuntimePermission accessDeclaredMembers)
	at com.google.appengine.runtime.Request.process-<unknown>(Request.java)
	at java.security.AccessControlContext.checkPermission(AccessControlContext.java:355)
	at java.security.AccessController.checkPermission(AccessController.java:567)
	at java.lang.SecurityManager.checkPermission(SecurityManager.java:549)
	at java.lang.SecurityManager.checkMemberAccess(SecurityManager.java:1679)
	at java.lang.Class.checkMemberAccess(Class.java:2174)
	at java.lang.Class.getDeclaredMethods(Class.java:1807)
	at java.lang.Class.getEnclosingMethod(Class.java:919)
	at sun.reflect.generics.scope.ClassScope.computeEnclosingScope(ClassScope.java:50)
	at sun.reflect.generics.scope.AbstractScope.getEnclosingScope(AbstractScope.java:74)
	at sun.reflect.generics.scope.AbstractScope.lookup(AbstractScope.java:90)
	at sun.reflect.generics.factory.CoreReflectionFactory.findTypeVariable(CoreReflectionFactory.java:109)
	at sun.reflect.generics.visitor.Reifier.visitTypeVariableSignature(Reifier.java:165)
	at sun.reflect.generics.tree.TypeVariableSignature.accept(TypeVariableSignature.java:43)
	at sun.reflect.generics.visitor.Reifier.reifyTypeArguments(Reifier.java:68)
	at sun.reflect.generics.visitor.Reifier.visitClassTypeSignature(Reifier.java:138)
	at sun.reflect.generics.tree.ClassTypeSignature.accept(ClassTypeSignature.java:49)
	at sun.reflect.generics.repository.ClassRepository.getSuperclass(ClassRepository.java:84)
	at java.lang.Class.getGenericSuperclass(Class.java:694)
	at com.sun.beans.TypeResolver.prepare(TypeResolver.java:274)
	at com.sun.beans.TypeResolver.<init>(TypeResolver.java:243)
	at com.sun.beans.TypeResolver.resolve(TypeResolver.java:172)
	at com.sun.beans.TypeResolver.resolveInClass(TypeResolver.java:93)
	at java.beans.FeatureDescriptor.getParameterTypes(FeatureDescriptor.java:385)
	at java.beans.MethodDescriptor.setMethod(MethodDescriptor.java:116)
	at java.beans.MethodDescriptor.<init>(MethodDescriptor.java:74)
	at java.beans.MethodDescriptor.<init>(MethodDescriptor.java:58)
	at java.beans.Introspector.getTargetMethodInfo(Introspector.java:1181)
	at java.beans.Introspector.getBeanInfo(Introspector.java:408)
	at java.beans.Introspector.getBeanInfo(Introspector.java:180)
	at groovy.lang.MetaClassImpl$15.run(MetaClassImpl.java:2937)
	at java.security.AccessController.doPrivileged(AccessController.java:63)
	at groovy.lang.MetaClassImpl.addProperties(MetaClassImpl.java:2935)
	at groovy.lang.MetaClassImpl.initialize(MetaClassImpl.java:2918)
	at org.codehaus.groovy.reflection.ClassInfo.getMetaClassUnderLock(ClassInfo.java:166)
	at org.codehaus.groovy.reflection.ClassInfo.getMetaClass(ClassInfo.java:182)
	at org.codehaus.groovy.runtime.metaclass.MetaClassRegistryImpl.getMetaClass(MetaClassRegistryImpl.java:214)
	at org.codehaus.groovy.runtime.InvokerHelper.getMetaClass(InvokerHelper.java:751)
	at groovy.lang.GroovyObjectSupport.<init>(GroovyObjectSupport.java:32)
	at groovy.lang.Closure.<init>(Closure.java:106)
	at groovy.lang.Closure.<init>(Closure.java:117)
	at org.codehaus.groovy.runtime.memoize.Memoize$1.<init>(Memoize.java:55)
	at org.codehaus.groovy.runtime.memoize.Memoize.buildMemoizeFunction(Memoize.java:55)
	at groovy.lang.Closure.memoize(Closure.java:530)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:43)
	at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:88)
	at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
	at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:272)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:885)
	at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:39)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:40)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:120)
	at Script1.run(Script1.groovy:7)
	at groovy.lang.GroovyShell.evaluate(GroovyShell.java:576)
	at groovy.lang.GroovyShell.evaluate(GroovyShell.java:614)
	at groovy.lang.GroovyShell.evaluate(GroovyShell.java:585)
	at groovy.lang.GroovyShell$evaluate.call(Unknown Source)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:40)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:124)
	at executor.run(executor.groovy:25)
	at groovy.util.GroovyScriptEngine.run(GroovyScriptEngine.java:515)
	at groovy.servlet.GroovyServlet$1.call(GroovyServlet.java:120)
	at org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.use(GroovyCategorySupport.java:99)
	at org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.access$300(GroovyCategorySupport.java:61)
	at org.codehaus.groovy.runtime.GroovyCategorySupport.use(GroovyCategorySupport.java:239)
	at groovy.servlet.GroovyServlet.service(GroovyServlet.java:129)
	at groovyx.gaelyk.GaelykServlet.super$5$service(GaelykServlet.groovy)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:43)
	at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:88)
	at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1055)
	at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuperN(ScriptBytecodeAdapter.java:127)
	at groovyx.gaelyk.GaelykServlet$_service_closure1.doCall(GaelykServlet.groovy:68)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:43)
	at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:88)
	at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
	at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:272)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:885)
	at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:66)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:149)
	at groovyx.gaelyk.GaelykServlet$_service_closure1.doCall(GaelykServlet.groovy)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:43)
	at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:88)
	at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
	at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:272)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:885)
	at groovy.lang.Closure.call(Closure.java:288)
	at groovy.lang.Closure.call(Closure.java:282)
	at org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.use(GroovyCategorySupport.java:111)
	at org.codehaus.groovy.runtime.GroovyCategorySupport.use(GroovyCategorySupport.java:250)
	at org.codehaus.groovy.runtime.DefaultGroovyMethods.use(DefaultGroovyMethods.java:415)
	at org.codehaus.groovy.runtime.dgm$740.invoke(Unknown Source)
	at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoMetaMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSite.java:307)
	at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:51)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:153)
	at groovyx.gaelyk.GaelykServlet.service(GaelykServlet.groovy:67)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:806)
	at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:43)
	at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoCachedMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:229)
	at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:52)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:128)
	at groovyx.gaelyk.routes.RoutesFilter.doFilter(RoutesFilter.groovy:156)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
	at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
	at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
	at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
	at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
	at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
	at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
	at org.mortbay.jetty.Server.handle(Server.java:326)
	at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
	at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
	at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
	at com.google.net.rpc.impl.BlockingApplicationHandler.handleRequest(BlockingApplicationHandler.java:24)
	at com.google.net.rpc.impl.RpcUtil.runRpcInApplication(RpcUtil.java:418)
	at com.google.net.rpc.impl.Server$RpcTask.runInContext(Server.java:572)
	at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:448)
	at com.google.tracing.TraceContext.runInContext(TraceContext.java:688)
	at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:326)
	at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:318)
	at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:446)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
	at java.lang.Thread.run(Thread.java:636)