class UserResponseDecorator {
    UserResponse decorate(UserModel model) {
        return UserResponse.builder()
            .username(model.username)
           .avatar(avatarService.getAvatarById(model.getAvatarId())
           .friends(friendService.getUserFriend(model.getId())
           .build();
   }
}

class NetworkProxy {
    void openUrl(String url) {
        validate(url);
        actualNetwork.openUrl(url);
    }
}