millheatclient-2.cs

public async Task<string> GetAuthorizationCode()
{
    httpClient.DefaultRequestHeaders.Add("access_key", access_key);
    httpClient.DefaultRequestHeaders.Add("secret_token", secret_token);

    var response = await httpClient.PostAsync("share/applyAuthCode", stringData);
    var result = await response.Content.ReadAsStringAsync();
    var jsonResult = JsonSerializer.Deserialize<ApplyAuthCodeResponse>(result);
    return jsonResult.Data.AuthorizationCode;
}