No resource classes found on a cxf Servlet

I have created a very simple cxf non-spring based Servlet which loads a javax.ws.rs.Application type.

Here is the web.xml:

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    version="2.5">

  <servlet>
        <servlet-name>CXFServlet</servlet-name>
        <servlet-class>
            org.apache.cxf.jaxrs.servlet.CXFNonSpringJaxrsServlet
        </servlet-class>
        <init-param>
            <param-name>javax.ws.rs.Application</param-name>
            <param-value>
                com.mycomp.cxf.TestApplication
            </param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>CXFServlet</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>

</web-app>

And here is the application:

public class TestApplication extends Application
{
    private final Set<Class<?>> classes = new HashSet<Class<?>>();
    private final Set<Object> singletons = new HashSet<Object>();

    public TestApplication() throws ServletException 
    {

    }

    @Override
    public Set<Class<?>> getClasses() 
    {
        return classes;
    }

    @Override
    public Set<Object> getSingletons() 
    {
        return singletons;
    }
}

The Servlet is failing to load due to: "No resource classes found" and i'm not sure why as it should be ok to have an empty set of classes in Application.

Here is the full stacktrace:

org.apache.cxf.jaxrs.AbstractJAXRSFactoryBean                          - No resource classes found
org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/test]  - StandardWrapper.Throwable
org.apache.cxf.service.factory.ServiceConstructionException
    at org.apache.cxf.jaxrs.JAXRSServerFactoryBean.create(JAXRSServerFactoryBean.java:122)
    at org.apache.cxf.jaxrs.servlet.CXFNonSpringJaxrsServlet.createServerFromApplication(CXFNonSpringJaxrsServlet.java:304)
    at org.apache.cxf.jaxrs.servlet.CXFNonSpringJaxrsServlet.loadBus(CXFNonSpringJaxrsServlet.java:72)
    at org.apache.cxf.transport.servlet.AbstractCXFServlet.init(AbstractCXFServlet.java:78)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1172)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:992)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4058)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4371)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:525)
    at com.springsource.osgi.webcontainer.tomcat.TomcatServletContainer.startWebApplication(TomcatServletContainer.java:120)
    at com.springsource.osgi.webcontainer.internal.StandardWebContainer$StandardWebApplication.start(StandardWebContainer.java:100)
    at com.springsource.osgi.webcontainer.extender.WebContainerBundleCustomizer.addingBundle(WebContainerBundleCustomizer.java:25)
    at org.osgi.util.tracker.BundleTracker$Tracked.customizerAdding(BundleTracker.java:440)
    at org.osgi.util.tracker.AbstractTracked.trackAdding(AbstractTracked.java:261)
    at org.osgi.util.tracker.AbstractTracked.track(AbstractTracked.java:233)
    at org.osgi.util.tracker.BundleTracker$Tracked.bundleChanged(BundleTracker.java:413)
    at org.eclipse.osgi.framework.internal.core.BundleContextImpl.dispatchEvent(BundleContextImpl.java:919)
    at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:227)
    at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:149)
    at org.eclipse.osgi.framework.internal.core.Framework.publishBundleEventPrivileged(Framework.java:1349)
    at org.eclipse.osgi.framework.internal.core.Framework.publishBundleEvent(Framework.java:1300)
    at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:380)
    at org.eclipse.osgi.framework.internal.core.AbstractBundle.start(AbstractBundle.java:284)
    at org.eclipse.osgi.framework.internal.core.AbstractBundle.start(AbstractBundle.java:276)
    at com.sap.core.js.deployer.watchservice.WARDeployer.deploy(WARDeployer.java:142)
    at com.sap.core.js.deployer.watchservice.FileSystemEventsListener.onChange(FileSystemEventsListener.java:26)
    at com.springsource.util.io.FileSystemChecker.notifyListeners(FileSystemChecker.java:182)
    at com.springsource.util.io.FileSystemChecker.check(FileSystemChecker.java:145)
    at com.sap.core.js.deployer.watchservice.WatchTask.run(WatchTask.java:29)
    at java.lang.Thread.run(Thread.java:679)
Caused by: javax.ws.rs.WebApplicationException
    at org.apache.cxf.jaxrs.AbstractJAXRSFactoryBean.checkResources(AbstractJAXRSFactoryBean.java:238)
    at org.apache.cxf.jaxrs.JAXRSServerFactoryBean.create(JAXRSServerFactoryBean.java:85)
    ... 31 more
10:41:54,580 [ERROR] org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/test]  - Servlet /test threw load() exception
javax.ws.rs.WebApplicationException
    at org.apache.cxf.jaxrs.AbstractJAXRSFactoryBean.checkResources(AbstractJAXRSFactoryBean.java:238)
    at org.apache.cxf.jaxrs.JAXRSServerFactoryBean.create(JAXRSServerFactoryBean.java:85)
    at org.apache.cxf.jaxrs.servlet.CXFNonSpringJaxrsServlet.createServerFromApplication(CXFNonSpringJaxrsServlet.java:304)
    at org.apache.cxf.jaxrs.servlet.CXFNonSpringJaxrsServlet.loadBus(CXFNonSpringJaxrsServlet.java:72)
    at org.apache.cxf.transport.servlet.AbstractCXFServlet.init(AbstractCXFServlet.java:78)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1172)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:992)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4058)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4371)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:525)
    at com.springsource.osgi.webcontainer.tomcat.TomcatServletContainer.startWebApplication(TomcatServletContainer.java:120)
    at com.springsource.osgi.webcontainer.internal.StandardWebContainer$StandardWebApplication.start(StandardWebContainer.java:100)
    at com.springsource.osgi.webcontainer.extender.WebContainerBundleCustomizer.addingBundle(WebContainerBundleCustomizer.java:25)
    at org.osgi.util.tracker.BundleTracker$Tracked.customizerAdding(BundleTracker.java:440)
    at org.osgi.util.tracker.AbstractTracked.trackAdding(AbstractTracked.java:261)
    at org.osgi.util.tracker.AbstractTracked.track(AbstractTracked.java:233)
    at org.osgi.util.tracker.BundleTracker$Tracked.bundleChanged(BundleTracker.java:413)
    at org.eclipse.osgi.framework.internal.core.BundleContextImpl.dispatchEvent(BundleCon开发者_运维知识库textImpl.java:919)
    at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:227)
    at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:149)
    at org.eclipse.osgi.framework.internal.core.Framework.publishBundleEventPrivileged(Framework.java:1349)
    at org.eclipse.osgi.framework.internal.core.Framework.publishBundleEvent(Framework.java:1300)
    at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:380)
    at org.eclipse.osgi.framework.internal.core.AbstractBundle.start(AbstractBundle.java:284)
    at org.eclipse.osgi.framework.internal.core.AbstractBundle.start(AbstractBundle.java:276)
    at com.sap.core.js.deployer.watchservice.WARDeployer.deploy(WARDeployer.java:142)
    at com.sap.core.js.deployer.watchservice.FileSystemEventsListener.onChange(FileSystemEventsListener.java:26)
    at com.springsource.util.io.FileSystemChecker.notifyListeners(FileSystemChecker.java:182)
    at com.springsource.util.io.FileSystemChecker.check(FileSystemChecker.java:145)
    at com.sap.core.js.deployer.watchservice.WatchTask.run(WatchTask.java:29)
    at java.lang.Thread.run(Thread.java:679)

You need to notify your environment of your serviceclasses. You first need to add the service class, otherwise you will just return null in getSingletons() So just change your now empty constructor to add the service class:

class TestApplication extends Application {
    public TestApplication() throws ServletException 
    {
      singletons.add( new com.example.MyService() )
    }
    ....
}

Well, I guess you can't have an empty set of classes as if I add one then it loads successfully, for example:

public TestApplication() throws ServletException 
{
        singletons.add(someClass);
}