Can't use java interfaces as models for unbound variables

[adrns]

Hi 👋,
I've been using interfaces to define classes for Oso - for the reason I'd like to use the @Immutable annotation from org.immutables - like so:

@Immutable
public interface Foo {
    boolean bar();
}

Then having this interface registered with oso, accessing the method in the .polar file:

some_func(foo: Foo) if
    foo.bar();

I get the following whenever Foo is an unbound variable:
Not supported: cannot call method on unbound variable ...

So I've fallen back to using POJOs with public final fields instead of interfaces in those cases where the object might be an unbound variable. Is there any plans on adding support for method calls on unbound variables?

(I didn't think a more detailed example is required for the sake of raising this question, but can provide one if necessary)