Only a week after the last revision Apple again updates the App Store Review Guidelines with a new section 29 on Apple Pay.
29. Apple Pay
Apps using Apple Pay must provide all material purchase information to the user prior to sale of any good or service or they will be rejected
Apps using Apple Pay must use Apple Pay branding and user interface elements correctly and as described in the Apple Pay Human Interface Guidelines or they will be rejected
Apps using Apple Pay as a purchasing mechanism may not offer goods or services that violate the law of any territory in which the good or service will be delivered and may not be used for any illegal purpose
Apps using Apple Pay may only share user data acquired via Apple Pay with third parties when provided to facilitate or improve delivery of goods and services or to comply with legal requirements