Generated function class injects dependencies in abstract base class instead of default implementation class

[SimonCockx]

When one function calls the other, the generated code will contain the injection of its dependencies, e.g.,

@ImplementedBy(Foo.FooDefault.class)
public abstract class Foo implements RosettaFunction {
    @Inject
    protected Bar bar; // its dependency is injected, but never used within the abstract base class.

    public static class FooDefault extends Foo {
        // this class actually uses `bar`, so the injection should happen here.
    }
}

This leads to superfluous injections for custom non-default implementations of Foo, which might not depend on Bar.