cglib/src/main/java/net/sf/cglib/beans/BeanGenerator.java
public void setSuperclass(Class superclass) {
        if (superclass != null && superclass.equals(Object.class)) {
            superclass = null;
        }
        this.superclass = superclass;
    }
public void setSuperclass(Class superclass) {
        if (superclass != null && superclass.equals(Object.class)) {
            superclass = null;
        }
        this.superclass = superclass;
    }
Set the class which the generated class will extend. The class
must not be declared as final, and must have a non-private
no-argument constructor.
@param superclass class to extend, or null to extend Object