public static IQueryable<Petshop.Data.Entities.Item> BySupplier(this IQueryable<Petshop.Data.Entities.Item> queryable, System.Int32 suppId)
 {
     return queryable.BySupplier(ComparisonOperator.Equals, suppId);
 }
        public static IQueryable<PetShop.Core.Data.Item> BySupplier(this IQueryable<PetShop.Core.Data.Item> queryable, int? supplier, params int?[] additionalValues)
        {
            var supplierList = new List<int?> { supplier };

            if (additionalValues != null)
                supplierList.AddRange(additionalValues);
            else
                supplierList.Add(null);

            if (supplierList.Count == 1)
                return queryable.BySupplier(supplierList[0]);

            return queryable.BySupplier(supplierList);
        }