A simple Spring Boot app used as a example for an article on W3C's Payment Request Api Specification written at the javamagazin
As an sample heidelpay's Flexipay invoice is integrated into the Payment-Request-Api. To see it in action use the sample shop.
Assuming Java (>= 8) is installed on your system, simply clone the repo and call gradlew bootRun. The Payment-methods will run under http://localhost:8081/heidelpay-invoice