code: public void setMinorTickMarkLengthFactor(final double FACTOR) {
          if (null == minorTickMarkLengthFactor) {
              _minorTickMarkLengthFactor = Helper.clamp(0.0, 1.0, FACTOR);
              fireUpdateEvent(REDRAW_EVENT);
          } else {
              minorTickMarkLengthFactor.set(FACTOR);
          }
      }
docs: The factor defines the length of the minor tick mark.
  It can be in the range from 0 - 1.
  
  @param FACTOR