问虽然参数“grant_type”是我请求体的一部分，但却收到了错误的请求

EN

public static async Task<string> GetToken()
{   ​   
    var client = new RestClient();
​
    var url = "https://login.microsoftonline.com/common/oauth2/token"
    var request = new RestRequest(url, Method.POST, DataFormat.Json);
​
    var body = new
    {
        grant_type = "password",
        client_id = "clientId",
        client_secret = "clientSecret",
        username = "user",
        password = "password",
        resource = "https://analysis.windows.net/powerbi/api"
    };
​
    request.AddJsonBody(body);
​
    var response = await client.ExecutePostAsync(request);
    return response.Content;
}