I noticed I can't call call get_discussion_posts using null for the second and third params. E.g.

despite the second and third params being nullable in the method signature. I'm guessing the expectation was for them to get defaults when called like this but it doesn't seem to work that way because of the web service validation. This needs a look in a follow up too, though it's certainly only a minor issue since we can call the method fine if we specify the args.