public static void AddTextPart <T>(
     this IParameterBag parameterBag,
     string value,
     T properties)
     where T : class
 {
     parameterBag.AddTextPart(value, null, properties);
 }
 public static void AddTextPart <T>(
     this IParameterBag parameterBag,
     string value,
     Encoding encoding,
     T properties)
     where T : class
 {
     parameterBag.AddTextPart(value, encoding, ParseProperties(properties));
 }