It is preferable that a DAO class (actually this looks more like an implementation of the Repository pattern), to not depend on validation, and instead take on the responsibility of persisting or retrieving the entity. It's too late to be validating at this point. At the same time, this should not be invoked in the `ContactRESTService` class; it's not the responsibility of that layer either. We need a layer in between for coordinating validation and persistence operations.