Sources:
GadgetRepository
Code:
@Repository(value = "gadgetRepository")
public interface GadgetRepository extends CrudRepository<Gadget, String>, QueryDslPredicateExecutor<Gadget> {
}
Gadget
Code:
@XmlRootElement
@Document(collection="gadget")
@PersistenceCapable
public class Gadget {
    @Id
    private String id;

    private String url;

    private Long timestamp;

    @DBRef(collection="status")
    private Status status;
GadgetService
Code:
QGadget gadget = QGadget.gadget;
        
        BooleanBuilder expressionBuilder = new BooleanBuilder();
        if (StringUtils.hasText(status)) {
            expressionBuilder.and(gadget.status.name.equalsIgnoreCase(status));
        }

        return (List<Gadget>) gadgetRepository.findAll(expressionBuilder);
Code:
gadgetService.getGadgets("APPROVED");
returns 0.

What is my mistake?