code: public static List<Integer> genIntegers(final int start, final int end) {
          final List<Integer> ret = new ArrayList<Integer>();
  
          for (int i = 0; i <= end; i++) {
              ret.add(i + start);
          }
  
          return ret;
      }
docs: Generates a list of integers from the specified start(inclusion) to the
  specified end(inclusion).
  
  @param start the specified start
  @param end   the specified end
  @return a list of integers