Comment by Proleps

why not use:

  public final class Article{
    public final String title;
    public final String author;
    public final List<String> tags;
    public Article(String title, String author, List<String> tags) {
      this.title = title;
      this.author = author;
      this.tags = tags;
    }
  }

Getters don't seem very useful on an immutable object.