Grails3 Webflow - Is there any working example?

Question

I am currently working with grails trying to setup a webflow. I used this (quite) old example: https://github.com/grails-samples/book-flow

When I run my grails app and want to start the flow, I just get the error:

Error: Page Not Found (404) Path: /book/shoppingCart

Is this example app outdated? Can someone give me a hint to setup a simple webflow with grails? Thanks