java.beans.DefaultPersistenceDelegate.instantiate(..) doesn't throw NPE

Specification for the following method says:

http://download.oracle.com/javase/7/docs/api/java/beans/DefaultPersistenceDelegate.html#instantiate%28java.lang.Object,%20java.beans.Encoder%29

Throws:
    NullPointerException - if out is null

This assertion is not satisfied. Please see the following code sample:


import java.beans.Encoder;
import java.beans.Expression;

public class DefaultPersistenceDelegate {

    public static void main(String[] args) {

        class MyPersistenceDelegate extends java.beans.DefaultPersistenceDelegate {
            @Override public Expression instantiate(Object oldInstance, Encoder out) {
                return super.instantiate(oldInstance, out);
            }
        }
        
        new MyPersistenceDelegate().instantiate(new Object(), (Encoder)null);
    }

}

The output will be blank.