public static void AddFilePart <T>(
     this IParameterBag parameterBag,
     string name,
     Stream stream,
     T properties)
     where T : class
 {
     parameterBag.AddFilePart(name, stream, ParseProperties(properties));
 }
 public static void AddFilePart(
     this IParameterBag parameterBag,
     string name,
     string fileName,
     Stream stream,
     IEnumerable <KeyValuePair <string, string> > properties = null)
 {
     parameterBag.AddFilePart(name, stream, new {
         filename = fileName,
     });
 }