code: public void drawCircle(Object parent, String name, Coordinate position, double radius, ShapeStyle style) {
  		if (isAttached()) {
  			Element circle = helper.createOrUpdateElement(parent, name, "oval", style);
  
  			// Real position is the upper left corner of the circle:
  			applyAbsolutePosition(circle, new Coordinate(position.getX() - radius, position.getY() - radius));
  
  			// width and height are both radius*2
  			int size = (int) (2 * radius);
  			applyElementSize(circle, size, size, false);
  		}
  	}
docs: Draw a circle on the <code>GraphicsContext</code>.
  
  @param parent
  parent group object
  @param name
  The circle's name.
  @param position
  The center position as a coordinate.
  @param radius
  The circle's radius.
  @param style
  The styling object by which the circle should be drawn.