using System;

using System.Text.Json;

using System.Text.Json.Serialization;

​

public class AlertResponse

{

    [JsonPropertyName("@class")]

    public string Class { get; set; }

}

​

public class Program

{

    public static void Main()

    {

        var result = JsonSerializer.Deserialize<AlertResponse>("{\"@class\":\"test\"}");

        Console.WriteLine(result.Class);

    }

}