code: public LocalTime minusMillis(int millis) {
          if (millis == 0) {
              return this;
          }
          long instant = getChronology().millis().subtract(getLocalMillis(), millis);
          return withLocalMillis(instant);
      }
docs: Returns a copy of this time minus the specified number of millis.
  <p>
  This LocalTime instance is immutable and unaffected by this method call.
  <p>
  The following three lines are identical in effect:
  <pre>
  LocalTime subtracted = dt.minusMillis(6);
  LocalTime subtracted = dt.minus(Period.millis(6));
  LocalTime subtracted = dt.withFieldAdded(DurationFieldType.millis(), -6);
  </pre>
  
  @param millis  the amount of millis to subtract, may be negative
  @return the new LocalTime minus the increased millis