code: public void setAreaFill(final ColorDef AREA_FILL_COLOR) {
          this.areaFill = AREA_FILL_COLOR;
          init(INNER_BOUNDS.width, INNER_BOUNDS.height);
          repaint(INNER_BOUNDS);
      }
docs: Sets the colordefinition of the area below the sparkline
  @param AREA_FILL_COLOR