self() in parent is sufficient

[marcusadrian]

No description provided.

[Piecewar]

No description provided.

when an abstract self() method is provided in parent
if you extends Builder in your subclass like this:
public static class Builder extends Pizza.Builder<Calzone.Builder> (wrong import or others)
other than
public static class Builder extends Pizza.Builder<Builder>
there will be a compile error when you implements self() method in subclass, then you will fix this error.

However, if self() method is not an abstract method in parent and use @SuppressWarnings on it,
you will find this problem until you try to create the object:

1. you will get a compile error when
   NyPizza pizza = new NyPizza.Builder(SMALL).addToppings(SAUSAGE).build();
2. or a ClassCastException occurs in runtime when
   Calzone calzone = new NyPizza.Builder(SMALL).addToppings(SAUSAGE).build();

but I'm not sure whether this example is right or not...