add the following code to the class org.jboss.resteasy.examples.contacts.services.ContactServiceImpl
in the project spring-hibernate-contacts-services:

-------------------
@Path("/subresource")
public Object subresource()

{ return new SubResource(); }

public static class SubResource {
@GET
public String get()

{ return "response from SubResource"; }

}
-------------------

rerun mvn install
rerun mvn jetty:run

open url in browser: http://localhost:9095/services/contactservice/subresource

throws
java.lang.IllegalArgumentException: object is not an instance of declaring class