code: public ClassDoc overriddenClass() {
          com.sun.javadoc.Type t = overriddenType();
          return (t != null) ? t.asClassDoc() : null;
      }
docs: Return the class that originally defined the method that
  is overridden by the current definition, or null if no
  such class exists.
  
  @return a ClassDocImpl representing the superclass that
  originally defined this method, null if this method does
  not override a definition in a superclass.