Where should the boundaries in a codebase go, and how do you know one is in the wrong place?
Answer it out loud before you open anything. The value of the flags below is in comparing them to what you actually said — including whether you named a cost, or only a principle.
The situation behind the question
A service follows a layered structure with domain, application, infrastructure and presentation packages, plus an interface and a mapper at each crossing. Adding a nullable field to a customer requires touching nine files, and every engineer on the team can recite the dependency rule.
What it is really testing
Whether the candidate can evaluate a boundary by what it contains rather than by whether it follows a named architecture. The scenario is a correctly implemented layered design that is nonetheless failing at the thing boundaries exist for.