When to use deep cloning?

 class Position{
   int x,y;
   Position(int x,int y){
    this.x = x;
    this.y = y;
   }

   int getX() {
     return x;
   }

   int getY() {
     return y;
   }

   void setX(int x) {
     this.x = x;
   }

   void setY(int y) {
      this.y = y;
   }
 }

 class Box{
        Position pos;
        Box(Position p){
           pos = new Position(p);
        }
        Position getPosition(){
          return pos;
        }
   }

class Room{
    Box box;
    Room(Box box){
        this.box = box;
    }
}

    public class Sample{
      public static void main(String args[]){
        Position pos = new Position(3,5);
        Box box = new Box(pos);
        pos.setX(5);
        System.out.println( box.getPosition().getX()); // Will return 5.
      }
    }