code: public Map<Long, Integer> computeDays(List<Long> sortedDates) {
  
          if (sortedDates.isEmpty()) {
              return Collections.<Long, Integer> emptyMap();
          }
          Map<Long, Integer> days = new HashMap<Long, Integer>();
          long lastDate = System.currentTimeMillis();
          int dayCounter = 0;
          for (Long dateObj : sortedDates) {
              long date = dateObj.longValue();
              long dayDifference = getDayDifference(lastDate, date);
              dayCounter += dayDifference;
              lastDate = date;
              days.put(dateObj, new Integer(dayCounter));
          }
          return days;
      }
docs: Given a descending list of dates represented as longs, this method computes a map from the dates
  to their age in (local) days.<p>
  
  @param sortedDates a descending list of dates represented as longs
  
  @return a map from dates to ages (measured in days)