Values.UpdateApiMappingRequestSourceUpdates an ApiMapping.
type nonrec t = {apiId : Id.t;The API identifier.
*)apiMappingId : string;The API mapping identifier.
*)apiMappingKey : SelectionKey.t option;The API mapping key.
*)domainName : string;The domain name.
*)stage : StringWithLengthBetween1And128.t option;The API stage.
*)}