code: public Shape createRadioButton(int x, int y, int diameter) {
          return createEllipseInternal(x, y, diameter, diameter);
      }
docs: Return a path for a radio button's concentric sections.
  
  @param  x        the X coordinate of the upper-left corner of the section
  @param  y        the Y coordinate of the upper-left corner of the section
  @param  diameter the diameter of the section
  
  @return a path representing the shape.