Tapestry IOC proxies have incorrect implementation when interface method uses a covariant return type (causes AbstractMethodError)

Here's a Junit 3 test case to demonstrate:

import junit.framework.TestCase;

import org.apache.tapestry5.ioc.Registry;
import org.apache.tapestry5.ioc.RegistryBuilder;
import org.apache.tapestry5.ioc.ServiceBinder;

public class ProxyText extends TestCase {

private Registry registry;

@Override
protected void setUp() throws Exception

{ RegistryBuilder builder = new RegistryBuilder(); builder.add(AppModule.class); registry = builder.build(); registry.performRegistryStartup(); }

public void testRegistryWorks()

{ assertEquals(new Integer(1), registry.getService(SuperIFace.class).get()); }

public static class AppModule {
public static void bind(ServiceBinder binder)

{ binder.bind(IFace.class, Impl.class); }

}

public interface SuperIFace

{ Number get(); }

public interface IFace extends SuperIFace

{ Integer get(); }


public static class Impl implements IFace {
public Integer get() { return 1; }
}
}



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The result is:
java.lang.AbstractMethodError: $IFace_1218d10684a.get()Ljava/lang/Number;

Note that if you change SuperIFace to:
public interface SuperIFace { Integer get(); }

the test works - demonstrating that the problem is to do with the use of a covariant return type in IFace.

BTW, this has turned up in code for testing where I want to create sub-interfaces that provide additional testing facilities for fake services and I need to control the particular types that are returned by the fake implementation.