[ARIES-1849] Aries proxy does not work with interface default methods

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: proxy-impl-1.1.2
• Fix Version/s: proxy-impl-1.1.4
• Component/s: Proxy
• Assignee: Jean-Baptiste Onofré
• Reporter: Nicolas Dutertry
• Created: 18/Oct/18 08:47
• Updated: 01/Mar/19 11:09
• Resolved: 14/Jan/19 05:37

Description

Since Java 8 it is possible to define default implementations inside interface definition.

It seems that Aries proxy is not compatible with interface default methods. As a result it is not possible to use a blueprint reference to a service implementing an interface with default method.

The following unit test demonstrates the issue :

import java.util.Collections;
import org.apache.aries.proxy.UnableToProxyException;
import org.apache.aries.proxy.impl.interfaces.InterfaceProxyGenerator;
import org.junit.Assert;
import org.junit.Test;

public class InterfaceProxyGeneratorTest {
    public static interface Service {
        String getName();
        
        default String getValue() {
            return "default";
        }
    }
    
    public static class ServiceImpl implements Service {
        @Override
        public String getName() {
            return "serviceimpl";
        }
        
        @Override
        public String getValue() {
            return "value";
        }
    }
    
    @Test
    public void testProxy() throws UnableToProxyException {
        ServiceImpl serviceImpl = new ServiceImpl();
        Assert.assertEquals("serviceimpl", serviceImpl.getName());
        Assert.assertEquals("value", serviceImpl.getValue());
        
        Service proxy = (Service)InterfaceProxyGenerator.getProxyInstance(
            null, null, Collections.singleton(Service.class),
            () -> {
                return serviceImpl;
            },
            null);
        
        Assert.assertNotNull(proxy);        
        Assert.assertEquals("serviceimpl", proxy.getName());
        Assert.assertEquals("value", proxy.getValue());
    }
}

Issue Links

• blocks: KARAF-5086 Java 8 default methods cause IncompatibleClassChangeError in blueprint
• links to: GitHub Pull Request #94