using System.Net.Http.Json;
using System.Text;

HttpClient client = new HttpClient();

HttpRequestMessage requestMessage=new HttpRequestMessage(HttpMethod.Get,"http://localhost:24240/api/route/jsonEndpoint");
requestMessage.Headers.Add("Authorization",$"Basic {Convert.ToBase64String(Encoding.UTF8.GetBytes("demi:password123"))}");
requestMessage.Content = JsonContent.Create(new Obj());
var resp=await client.SendAsync(requestMessage);
Console.WriteLine(await resp.Content.ReadAsStringAsync());


public class Obj
{
    public string Name {get;set;}="Demetria Devonne Lovato";

    public DateTime Birthday {get;set;}=new DateTime(1992,8,20);
}