public String build() {
		Class<GroupRequest> clazz = GroupRequest.class;
		StringBuilder result = new StringBuilder();
		try {
			Field[] fields = clazz.getDeclaredFields();
			for (int i = 0; i < fields.length; i++) {
				if (fields[i].isAnnotationPresent(RequestParameter.class)) {
					String title = fields[i].getAnnotation(
							RequestParameter.class).title();
					Object value = fields[i].get(request);
					if (value != null) {
						if (result.length() > 0) {
							result.append("&");
						}
						result.append(title).append("=").append(value);

					}
				}
			}
		} catch (IllegalArgumentException e) {
			Throwables.propagate(e);
		} catch (IllegalAccessException e) {
			Throwables.propagate(e);
		}
		return result.toString();
	}