code: private static List<String> getYearSpan(int startYear, int endYear) {
  
          List<String> result = new ArrayList<String>();
          for (int i = startYear; i <= endYear; i++) {
              String dateStr = String.valueOf(i);
              result.add(dateStr);
          }
          return result;
      }
docs: Calculate a span of years for the optimized date range search.<p>
  
  The result will contain dates formatted like "yyyy", for example "2008".<p>
  
  @param startYear the start year
  @param endYear the end year
  
  @return a span of years for the optimized date range search