Replaces the suppression lists attached to a broadcast with the supplied set (a full replace, not an incremental add). suppression_uuids must be present: the array you send becomes the broadcast's complete suppression set, and any list previously attached but not re-sent is detached. Send [] to detach all of them. Every UUID must belong to a suppression list in the authenticated account -- if any one does not, the request is rejected with 422 and the broadcast keeps the lists it already had. suppression_uuids was previously an optional field on update_broadcast, which now rejects it. Its shape is unchanged; only its home and the fact that it is required have changed.