Fazer consulta passando JSON como parâmetro VRaptor + AngularJS

Fala galera!

Estou começando a estudar VRaptor + AngularJS e estou com algumas dúvidas…

Estou querendo fazer uma consulta passando como parâmetro um JSON:
AngularJS Code:

$scope.buscar = function () { var filtro = angular.toJson({ filtro : { codEmp: $scope.empresa.codEmp, dtInicio: $scope.dataInicial, dtFim: $scope.dataFinal } }); $http.get('/Site/meta/minhaMeta/' + filtro).success(function(data){ alert('Entrou!') $scope.metas = data; $scope.show = true; }); };

VRaptor Code:

@Get("/meta/minhaMeta/{filtro}") @Consumes("application/json") public void busca(final FiltroMeta filtro) { List<Meta> metas = this.dao.find(filtro); result.use(Results.json()).withoutRoot().from(metas).include("empresa", "natureza").serialize(); }

Mas dá o seguinte erro:

java.lang.NullPointerException at br.com.caelum.vraptor.observer.DeserializingObserver.mime(DeserializingObserver.java:102) at br.com.caelum.vraptor.observer.DeserializingObserver.deserializes(DeserializingObserver.java:79) 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:606) at org.jboss.weld.injection.MethodInjectionPoint.invokeOnInstanceWithSpecialValue(MethodInjectionPoint.java:93) at org.jboss.weld.event.ObserverMethodImpl.sendEvent(ObserverMethodImpl.java:266) at org.jboss.weld.event.ObserverMethodImpl.sendEvent(ObserverMethodImpl.java:253) at org.jboss.weld.event.ObserverMethodImpl.notify(ObserverMethodImpl.java:232) at org.jboss.weld.event.ObserverNotifier.notifyObserver(ObserverNotifier.java:169) at org.jboss.weld.event.ObserverNotifier.notifyObserver(ObserverNotifier.java:165) at org.jboss.weld.event.ObserverNotifier.notifyObservers(ObserverNotifier.java:119) at org.jboss.weld.event.ObserverNotifier.fireEvent(ObserverNotifier.java:112) at org.jboss.weld.event.EventImpl.fire(EventImpl.java:83) at br.com.caelum.vraptor.core.DefaultInterceptorStack.start(DefaultInterceptorStack.java:90) at br.com.caelum.vraptor.core.DefaultInterceptorStack$Proxy$_$$_WeldClientProxy.start(Unknown Source) at br.com.caelum.vraptor.observer.RequestHandlerObserver.handle(RequestHandlerObserver.java:86) 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:606) at org.jboss.weld.injection.MethodInjectionPoint.invokeOnInstanceWithSpecialValue(MethodInjectionPoint.java:93) at org.jboss.weld.event.ObserverMethodImpl.sendEvent(ObserverMethodImpl.java:266) at org.jboss.weld.event.ObserverMethodImpl.sendEvent(ObserverMethodImpl.java:253) at org.jboss.weld.event.ObserverMethodImpl.notify(ObserverMethodImpl.java:232) at org.jboss.weld.event.ObserverNotifier.notifyObserver(ObserverNotifier.java:169) at org.jboss.weld.event.ObserverNotifier.notifyObserver(ObserverNotifier.java:165) at org.jboss.weld.event.ObserverNotifier.notifyObservers(ObserverNotifier.java:119) at org.jboss.weld.event.ObserverNotifier.fireEvent(ObserverNotifier.java:112) at org.jboss.weld.event.EventImpl.fire(EventImpl.java:83) at br.com.caelum.vraptor.VRaptor.doFilter(VRaptor.java:116) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745)

Alguma luz?