bug(*): fix orders json data, make orderdto custoemrid and shipperid nullable

bug(*): fix orders json data, make orderdto custoemrid and shipperid nullable

Author: ddidgdimitrov-infragistics

NorthwindCRUD/Models/Contracts/IOrder.cs

@@ -11,7 +11,7 @@ public interface IOrder
 
         int EmployeeId { get; set; }
 
-        int ShipperId { get; set; }
+        int? ShipperId { get; set; }
 
         string OrderDate { get; set; }
 

NorthwindCRUD/Models/Dtos/OrderDto.cs

@@ -9,11 +9,11 @@ public class OrderDto : IOrder
         public int OrderId { get; set; }
 
         [Required(ErrorMessage = "CustomerId is required.")]
-        public string CustomerId { get; set; }
+        public string? CustomerId { get; set; }
 
         public int EmployeeId { get; set; }
 
-        public int ShipperId { get; set; }
+        public int? ShipperId { get; set; }
 
         [DataType(DataType.Date, ErrorMessage = "OrderDate must be a valid date.")]
         public string OrderDate { get; set; }