add new method drawDecoration

src/main/java/shape/BorderDecorator.java

 package shape;
 
-public class BorderDecorator {
+import javafx.scene.canvas.GraphicsContext;
+import javafx.geometry.Point2D;
+
+import javafx.scene.paint.Color;
+
+import javax.swing.border.Border;
+
+
+public class BorderDecorator extends Decorator{
+    private double radius;
+
+    public BorderDecorator(Shape decoratedShape, double radius){
+        super(decoratedShape);
+        this.radius=radius;
+    }
+
+
+    @Override
+    protected void drawDecoration(GraphicsContext graphicsContext) {
+        for (int i=0 ; i<decoratedShape.pointsCount();i++){
+            Point2D point = decoratedShape.point(i);
+            graphicsContext.strokeOval(point.getX()-radius,point.getY()-radius,radius*2,radius*2);
+        }
+    }
+    public void draw(GraphicsContext graphicsContext){
+        decoratedShape.draw(graphicsContext);
+        drawDecoration(graphicsContext);
+    }
 }