Actually that's a great question! I wouldn't believe any brochure, salesman or sales document. They've all been known to be wrong (and some just plain lie). This requires jacking the frame, removing the wheel and removing the drum - this is oversimplified and more work than I described for EACH wheel, which is why you are asking your question.
I think you're just gonna have to look, or to answer your question, have someone else look
. I recall a post somewhere that an owner found he had a mixed bag. One axle had them, one axle didn't because when he had an axle problem and the axle assembly was replaced with a system that did not have adjustable brakes and only checked when he had a tire problem. I hope I'm getting the story right, but the point is I don't know any other way to know unless you take each wheel off and look. Don't believe anyone or any piece of paper.
Anyway, that's what I would do. I hope someone else has an easier way to tell that includes ACTUAL verification at the brake. FYI - This does not apply to disc brakes, only drum brakes.