code: public void setEdgeColor(ColorSet colorSet) {
          if (edgeColor == null) edgeColor = new RGBColor(0.0, 0.0, 0.0);
          setGradation(true);
          this.edgeColor = RGBColor.color(colorSet);
      }
docs: Sets the colorSet of the edge of this Arc.
  
  @param colorSet The colorSet of the edge of the Arc.