protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
            var amazon = EfMerchantRepository.CreateMerchant_Amazon();
            var apple  = EfMerchantRepository.CreateMerchant_Apple();

            modelBuilder.Entity <Merchant>()
            .HasData(amazon);
            modelBuilder.Entity <Merchant>()
            .HasData(apple);
        }
        public void LoadMerchants()
        {
            Merchants.Add(EfMerchantRepository.CreateMerchant_Amazon());

            Merchants.Add(EfMerchantRepository.CreateMerchant_Apple());
        }