How to post List of data in asp.net web api

I want to post my json data from Xamarin.Forms application to my asp.net web api.

My Models Class

public class MyModel2
{
    public int Id { get; set; }
    public string ShopName { get; set; }
    public List<Order2> ListOrder { get; set; }
}

public class Order2
{
    public int Id { get; set; }
    public string ProductName { get; set; }
}

My Controller code is below :

public class MyModel2Controller : ApiController
{
    private MPTContext db = new MPTContext();

    // GET: api/MyModel2
    public IQueryable<MyModel2> GetMyModel2()
    {
        return db.MyModel2;
    }

    // GET: api/MyModel2/5
    [ResponseType(typeof(MyModel2))]
    public async Task<IHttpActionResult> GetMyModel2(int id)
    {
        MyModel2 myModel2 = await db.MyModel2.FindAsync(id);
        if (myModel2 == null)
        {
            return NotFound();
        }

        return Ok(myModel2);
    }

    // PUT: api/MyModel2/5
    [ResponseType(typeof(void))]
    public async Task<IHttpActionResult> PutMyModel2(int id, MyModel2 myModel2)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }

        if (id != myModel2.Id)
        {
            return BadRequest();
        }

        db.Entry(myModel2).State = EntityState.Modified;

        try
        {
            await db.SaveChangesAsync();
        }
        catch (DbUpdateConcurrencyException)
        {
            if (!MyModel2Exists(id))
            {
                return NotFound();
            }
            else
            {
                throw;
            }
        }

        return StatusCode(HttpStatusCode.NoContent);
    }

    // POST: api/MyModel2
    [ResponseType(typeof(MyModel2))]
    public async Task<IHttpActionResult> PostMyModel2(MyModel2 myModel2)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }

        db.MyModel2.Add(myModel2);
        await db.SaveChangesAsync();

        return CreatedAtRoute("DefaultApi", new { id = myModel2.Id }, myModel2);
    }

    // DELETE: api/MyModel2/5
    [ResponseType(typeof(MyModel2))]
    public async Task<IHttpActionResult> DeleteMyModel2(int id)
    {
        MyModel2 myModel2 = await db.MyModel2.FindAsync(id);
        if (myModel2 == null)
        {
            return NotFound();
        }

        db.MyModel2.Remove(myModel2);
        await db.SaveChangesAsync();

        return Ok(myModel2);
    }

    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            db.Dispose();
        }
        base.Dispose(disposing);
    }

    private bool MyModel2Exists(int id)
    {
        return db.MyModel2.Count(e => e.Id == id) > 0;
    }
}

My RestService Code is below:

MyModel2 model1:

public async Task<MyModel2> SaveOrder()
{
    model1 = new MyModel2
    {
        ShopName = "MMSHop",
        ListOrder = new List<Order2>()
        {
            new Order2
            {
                ProductName = "MMPRoduct"
            }
        }
    };
    var data = JsonConvert.SerializeObject(model1);
    var content = new StringContent(data, Encoding.UTF8, "application/json");
    var result = await client.PostAsync(MainUrl, content);
    return model1;
}

My Button Event Handler is

MyModel2 OOmodel;
private async void OnOrderPlace(object sender, EventArgs e)
{
    OOmodel = await OOrest.SaveOrder();
}

When I press the button I get json data like

Json Result Image:

but on my asp.net web api result seems like that

Asp.net Web API result: as you see ListOrder is null however in my application I am also sending its data. I also try to use postman from that i get 201 code (successful or generated) also in my Server Explorer --> Order2 Table i get poster values in Orders2 Table but not on server.