self() in parent is sufficient

src/effectivejava/chapter2/item2/hierarchicalbuilder/Calzone.java

@@ -15,8 +15,6 @@ public Builder sauceInside() {
         @Override public Calzone build() {
             return new Calzone(this);
         }
-
-        @Override protected Builder self() { return this; }
     }
 
     private Calzone(Builder builder) {

src/effectivejava/chapter2/item2/hierarchicalbuilder/NyPizza.java

@@ -18,7 +18,6 @@ public Builder(Size size) {
             return new NyPizza(this);
         }
 
-        @Override protected Builder self() { return this; }
     }
 
     private NyPizza(Builder builder) {

src/effectivejava/chapter2/item2/hierarchicalbuilder/Pizza.java

@@ -18,8 +18,13 @@ public T addTopping(Topping topping) {
 
         abstract Pizza build();
 
-        // Subclasses must override this method to return "this"
-        protected abstract T self();
+        @SuppressWarnings("unchecked")
+        protected T self() {
+            // this is always of type T
+            // so there is no need to override
+            // self in subclasses
+            return (T) this;
+        }
     }
 
     Pizza(Builder<?> builder) {