Payroll Case Study with UI, DB, etc?

I'm currently going through the payroll case study from Agile Software Development. Does anyone know if there is full example out there with not just the backend models, but also a database and a UI? I'm curious to see how it all connects together.

The best I've seen is an implementation with an Application.java, but even this is not clear to me how it would hook up with a frontend https://github.com/bysoul/Payroll/blob/master/src/main/java/com/payroll/payrollapp/PayrollApplication.java#L12

I ask because this is a fairly different way than I'd normally approach system design, so I'm trying to wrap my head around what the final product would look like vs. something I might come up with not having read this book.