code: public static ZoneOffset ofTotalSeconds(int totalSeconds) {
          if (Math.abs(totalSeconds) > MAX_SECONDS) {
              throw new DateTimeException("Zone offset not in valid range: -18:00 to +18:00");
          }
          if (totalSeconds % (15 * SECONDS_PER_MINUTE) == 0) {
              Integer totalSecs = totalSeconds;
              ZoneOffset result = SECONDS_CACHE.get(totalSecs);
              if (result == null) {
                  result = new ZoneOffset(totalSeconds);
                  SECONDS_CACHE.putIfAbsent(totalSecs, result);
                  result = SECONDS_CACHE.get(totalSecs);
                  ID_CACHE.putIfAbsent(result.getId(), result);
              }
              return result;
          } else {
              return new ZoneOffset(totalSeconds);
          }
      }
docs: Obtains an instance of {@code ZoneOffset} specifying the total offset in seconds
  <p>
  The offset must be in the range {@code -18:00} to {@code +18:00}, which corresponds to -64800 to +64800.
  
  @param totalSeconds  the total time-zone offset in seconds, from -64800 to +64800
  @return the ZoneOffset, not null
  @throws DateTimeException if the offset is not in the required range