Embedded List в room

Имеется модель класса

@Entity
@TypeConverters({
    ConverterList.class, 
    ConverterListObject.CardsOBJ.class,
    ConverterListObject.LoansOBJ.class, 
    ConverterListObject.CountriesOBJ.class,
    ConverterListObject.Cards_creditOBJ.class, 
    ConverterListObject.CreditsOBJ.class,
    ConverterListObject.Cards_installmentsOBJ.class, 
    ConverterListObject.Cards_debitOBJ.class,
    })
public class DB {

    @PrimaryKey(autoGenerate = true)
    private long id;

    private List<String> news;

    private List<Cards> cards;

    @Embedded(prefix = "ru")
    private Ru ru;

    private List<String> documents;

    private List<Loans> loans;
}

Пример конвертора

public class ConverterListObject {

    public static class CardsOBJ {
        @TypeConverter
        public static List<Cards> stringToCards(String json) {
            Gson gson = new Gson();
            Type type = new TypeToken<List<Cards>>() {
            }.getType();
            List<Cards> measurements = gson.fromJson(json, type);
            return measurements;
        }

        @TypeConverter
        public static String CardsToString(List<Cards> list) {
            Gson gson = new Gson();
            Type type = new TypeToken<List<Cards>>() {
            }.getType();
            String json = gson.toJson(list, type);
            return json;
        }
    }

DB.class have constructor

public DB() {

    public DB(long id, List<String> news, List<Cards> cards, Ru ru, List<String> documents, ...) {
        this.id = id;
        this.news = news;
        this.cards = cards;
        this.ru = ru;
        this.documents = documents;
        this.loans = loans;
        this.countries = countries;
}

Но код не компилируется а выдает ошибку, неважно есть конструктор или нет Entities and POJOs must have a usable public constructor. You can have an empty constructor or a constructor whose parameters match the fields (by name and type). - java.util.List