java虚拟机有关methodHandle的代码问题？

以下代码书上说是输出“i am grandfather”，但远行实际输出为“i am father”
class Test {
class GrandFather {
void thinking() {
System.out.println("i am grandfather");
}
}
class Father extends GrandFather {
void thinking() {
System.out.println("i am father");
}
}
class Son extends Father {
void thinking() {
try {
MethodType mt = MethodType.methodType(void.class);
MethodHandle mh = lookup().findSpecial(GrandFather.class, 
"thinking", mt, getClass());
mh.invoke(this);
} catch (Throwable e) {
}
}
}
public static void main(String[] args) {
    (new Test().new Son()).thinking();
}
}

求解！