How to use Stream.map()

After.java

  static final Ordering<Banner> RANDOM_ORDER = Ordering.natural()
    .onResultOf((Banner b) -> b.getWeight() * randomGenerator.nextDouble())
    .reverse();

  public List<BannerViewModel> getBanners(List<Banner> banners, final String language) {
    final List<Banner> selectedList = RANDOM_ORDER.greatestOf(banners, MAX_SIZE);
    return selectedList.stream().map(b ->
      BannerViewModel.builder()
        .id(b.getId())
        .href(getHref(b, language))
        .image(getImageForLanguage(b, language))
        .build()
    ).collect(Collectors.toList());
  }

Before.java

  static final Ordering<Banner> RANDOM_ORDER = Ordering.natural()
    .onResultOf((Banner b) -> b.getWeight() * randomGenerator.nextDouble())
    .reverse();

  public List<BannerViewModel> getBanners(List<Banner> banners, final String language) {
    final List<Banner> selectedList = RANDOM_ORDER.greatestOf(banners, MAX_SIZE);
    final List<BannerViewModel> returnList = new ArrayList<>();

    selectedList.forEach(b ->
      returnList.add(
        BannerViewModel.builder()
          .id(b.getId())
          .href(getHref(b, language))
          .image(getImageForLanguage(b, language)).build())
      );
  }