public void Serialize(Newtonsoft.Json.JsonWriter writer, object obj, Newtonsoft.Json.JsonSerializer serializer)
        {
            if (obj == null)
            {
                return;
            }

            var item = (Upload)obj;

            writer.WriteProperty(RedmineKeys.CONTENT_TYPE, item.ContentType);
            writer.WriteProperty(RedmineKeys.FILENAME, item.FileName);
            writer.WriteProperty(RedmineKeys.TOKEN, item.Token);
            writer.WriteProperty(RedmineKeys.DESCRIPTION, item.Description);
        }