code: public static @Nullable Date mostRecent(@Nullable Resource @NotNull... resources) {
      Date[] dates = new Date[resources.length];
      for (int i = 0; i < resources.length; i++) {
        dates[i] = get(resources[i]);
      }
      return mostRecent(dates);
    }
docs: Finds the most recent modification date of all specified resources
  @param resources multiple resources (typically jcr:content nodes of cq-pages or rendition resources)
  @return the most recent date (or null if none of the resources has a modification date)