private List<Catalog> getSeriesEpisodes(Catalog series, int season) {
    List<Catalog> catalogs = new ArrayList<>();
    Catalog e1 =
        new Catalog(
            1,
            "The Empty Hearse",
            series.getReleaseDate(),
            series.getAverageRating(),
            CatalogType.EPISODE);
    buildEpisodeMetadata(series, season, e1);

    Catalog e2 =
        new Catalog(
            2,
            "The Sign of Three",
            series.getReleaseDate(),
            series.getAverageRating(),
            CatalogType.EPISODE);
    buildEpisodeMetadata(series, season, e1);

    Catalog e3 =
        new Catalog(
            3,
            "His Last Vow",
            series.getReleaseDate(),
            series.getAverageRating(),
            CatalogType.EPISODE);
    buildEpisodeMetadata(series, season, e1);

    catalogs.add(e1);
    catalogs.add(e2);
    catalogs.add(e3);
    return catalogs;
  }
 private void buildEpisodeMetadata(Catalog series, int season, Catalog e1) {
   e1.addMetadata("seriesId", String.valueOf(series.getId()));
   e1.addMetadata("seriesTitle", series.getTitle());
   e1.addMetadata("seriesSeason", String.valueOf(season));
 }