class ForeignApi{
   public void hello(){ // need override}
}

class NewApi extends ForeignApi{
 @Override
 public void hello() { //new thing}
}

class God{
 public void xxxFunction(ForeignApi api){
  // need override
  api.hello();
 }

 void main(){
  ForeignApi api=new NewApi()
  xxxFunction(api);
 }
}