class LikesFeed extends FlattenableFeed<List<Like>> {

    @Override
    public List<Like> flatten() {
        if(users == null) {
            return new ArrayList<>();
        }
        for(Like like: likes) {
            like.setUser(users.get(like.getUserId()));
            like.setPost(posts.get(like.getPostId()));
        }
        return likes;
    }

}