OptionalassignmentHow the item is being assigned
OptionalbillingThe id of the subscription used for purchase
OptionalitemThe marketplace id (publisherName.extensionName) for the item
OptionaloperationThe type of operation, such as install, request, purchase
OptionalpropertiesAdditional properties which can be added to the request.
OptionalquantityHow many licenses should be purchased
OptionaltargetsA list of target guids where the item should be acquired (installed, requested, etc.), such as account id
Contract for handling the extension acquisition process