Suppose you have a Java interface with a default method like this:

public interface Foo {
    default String someMethod() {
        return "default";
    }
}

as well as some method which expects an instance of this interface:

public static void consumeFoo(Foo f) {
    logger.info(f.someMethod());
}

If you try to wrap a JS object as an instance of this interface and override the default method:

consumeFoo({
    someMethod: () => "overridden"
})

it does not work as expected: The default implementation will be called rather than the function given by the JS object, logging "default" rather than "overridden".

I believe the problem is in these lines: The default method will be called for any defaulted interface method, regardless of whether the target overrides it.

Rhino version: 2101.2.7-build.74, KubeJS version: 2101.7.2-build.233, Minecraft 1.21.1