Working PECS heritage

pecs.java

public class ContravariantHeritage {

    public static void main(String[] args) {
        new ContravariantHeritage().launch();
    }
    void launch() {
        List<Bamboo> food = new OhPanda().getMeals();
        System.out.println(food);
    }


    abstract class Restaurant<F extends Food>  {
        Kitchen<F> kitchen;

        public Restaurant(Kitchen kitchen) {
            this.kitchen = kitchen;
        }

        abstract List<? extends Food> getMeals();
    }

    interface Kitchen<F extends Food>  {
        void build(List<? super F> plate);
    }

    class PandaKitchen implements Kitchen<Bamboo>{

        @Override
        public void build(List<? super Bamboo> dessert) {
            System.out.println("Adding Bamboo to plate");
            dessert.add(new Bamboo());
        }
    }

    class MeatKitchen implements Kitchen<Meat>{

        @Override
        public void build(List<? super Meat> plate) {
            System.out.println("Adding Meat to plate");
            plate.add(new Meat());
        }
    }


    class OhPanda extends Restaurant {

        public OhPanda() {
            super(new PandaKitchen());
        }

        @Override
        List<Bamboo> getMeals() {
            List<Bamboo> bamboos = new ArrayList<>();
            this.kitchen.build(bamboos);
            return bamboos;
        }
    }


    class Food {
        @Override
        public String toString() {
            return this.getClass().getSimpleName();
        }
    }

    class Meat extends Food {}
    class Bamboo extends Food {}
}

You can get rid of ? extends ...
`
import java.util.ArrayList;
import java.util.List;

public class ContravariantHeritage {

public static void main(String[] args) {
	new ContravariantHeritage().launch();
}
void launch() {
    List<Bamboo> food = new OhPanda().getMeals();
    System.out.println(food);
}


abstract class Restaurant<F extends Food>  {
    Kitchen<F> kitchen;

    public Restaurant(Kitchen kitchen) {
        this.kitchen = kitchen;
    }

    abstract List<? extends Food> getMeals();
}

interface Kitchen<F extends Food>  {
    void build(List<F> plate);
}

class PandaKitchen implements Kitchen<Bamboo>{

    @Override
    public void build(List<Bamboo> dessert) {
        System.out.println("Adding Bamboo to plate");
        dessert.add(new Bamboo());
    }
}

class MeatKitchen implements Kitchen<Meat>{

    @Override
    public void build(List<Meat> plate) {
        System.out.println("Adding Meat to plate");
        plate.add(new Meat());
    }
}


class OhPanda extends Restaurant {

    public OhPanda() {
        super(new PandaKitchen());
    }

    @Override
    List<Bamboo> getMeals() {
        List<Bamboo> bamboos = new ArrayList<>();
        this.kitchen.build(bamboos);
        return bamboos;
    }
}


class Food {
    @Override
    public String toString() {
        return this.getClass().getSimpleName();
    }
}

class Meat extends Food {}
class Bamboo extends Food {}

}`