code: public static @Nullable Date mostRecent(Date @NotNull... dates) {
      Date mostRecentDate = null;
      for (Date date : dates) {
        if (date != null && (mostRecentDate == null || date.after(mostRecentDate))) {
          mostRecentDate = date;
        }
      }
      return mostRecentDate;
    }
docs: Returns the most recent of the specified dates
  @param dates Dates
  @return the most recent (or null if all dates were null)