如何使用System.Net.HttpClient发布复杂类型？

using System.Net.Http;
using System.Text;
using System.Threading.Tasks;

public class HttpClientExample
{
    public async Task<string> GetComplexTypeAsync()
    {
        var httpClient = new HttpClient();
        var content = new ComplexType();
        content.Property1 = "Hello";
        content.Property2 = 42;
        content.Property3 = "World";

        var json = JsonConvert.SerializeObject(content);
        var contentString = new StringContent(json, Encoding.UTF8, "application/json");

        var response = await httpClient.PostAsync("http://example.com/api/complex-type", contentString);
        var result = await response.Content.ReadAsStringAsync();

        return result;
    }
}

public class ComplexType : IHttpContent
{
    public string Property1 { get; set; }
    public int Property2 { get; set; }
    public string Property3 { get; set; }
}