code: public void plusMilliSeconds(long delta)
      {
          plusNanoSeconds(Math.floorMod(delta, 1000)*1000000);
          plusSeconds(Math.floorDiv(delta, 1000));
      }
docs: Adds delta milliseconds. Delta can be negative. Month, year, day, hour,
  minute, seconds and nanoSecond fields are affected.
  @param delta