code: @Override
    public int compareTo(Duration otherDuration) {
      int cmp = TimeUtils.compareLongs(getSeconds(), otherDuration.getSeconds());
      if (cmp != 0) {
        return cmp;
      }
      return TimeUtils.compareLongs(getNanos(), otherDuration.getNanos());
    }
docs: Compares this {@code Duration} to the specified {@code Duration}.
  
  @param otherDuration the other {@code Duration} to compare to, not {@code null}.
  @return the comparator value: zero if equal, negative if this duration is smaller than
  otherDuration, positive if larger.
  @throws NullPointerException if otherDuration is {@code null}.