code: public void setUnit(final String UNIT) {
          if (null == unit) {
              _unit = UNIT;
              fireTileEvent(VISIBILITY_EVENT);
              fireTileEvent(REDRAW_EVENT);
          } else {
              unit.set(UNIT);
          }
      }
docs: Sets the unit of the gauge. This unit will usually only be
  visible if it is not empty.
  
  @param UNIT