Demo deadlock with getting async result in ASP.NET 4.x

DemoDeadlockController.cs

public class DemoDeadlockController : ApiController
{
    [HttpGet]
    public HttpResponseMessage DownloadPage()
    {
        var task = MyDownloadPageAsync("https://www.huanlintalk.com");
        var content = task.Result;
        return Request.CreateResponse($"網頁長度: {content.Length}");
    }

    private static HttpClient _httpClient = new HttpClient();
 
    private async Task<string> MyDownloadPageAsync(string url)
    {
        string content = await _httpClient.GetStringAsync(url);
        return content;
    }
}