I'm trying to share and reuse fields across spaces. I have set them up via the GUI. When I list custom fields for my space, I can see they "Belong to" Space A, and have been "Added to" Space A and Space B. But if I try to list the fields in Space B via the API, they don't show up. Is there a way to get the custom-fields "Added to" a space, even if they're not owned by it?