Impression
@Serializable
This object describes an ad placement or impression being auctioned.
A single BidRequest can include multiple Impression objects, a use case for which might be an exchange that supports selling all ad positions on a given page. Each Impression object has a required ID so that bids can reference them individually. The presence of Banner, Video, or Native, subordinate to the Imp object indicates the type of impression being offered. The publisher can choose one such type which is the typical case or mix them at their discretion. However, any given bid for the impression must conform to one of the offered types.