This is a very small prototype of a simple ABAP CDS, enhanced with virtual elements. The example was made on Business Technology Platform with a free trial account so it should be easy to work with it. I used some blogs like this one and this one to create the example but I experienced some differences since ABAP CDS is now working with view entities.
Good starting points to explore the example are the by virtual elements enhanced ABAP CDS and the ABAP class that contains the logic.