FackelAB (1) [Avatar] Offline
The Listing in Chapter 2.1.2 is not possible to compile at this state.
There are missing a class (Taco) and the method (filterByType).

The Taco-Class should be first shown in the chapter 2.1.1 "Establishing the domain", just before the Listing 2.1 (Ingridient).
I think this class is the essential class of the domain.

And in the provided sources there is no class Taco (there is the name Design).