ReflectionUtils.doWithFields: Iterative Reflection on Superclass Data Fields Issue

I need to do a common action on data members of a certain type (Attachment) declared not just in this Form but inherited from super-classes of this Form.

If I were to use Java reflection head-on I would have to iterate through getSuperclass() until I hit a NULL superclass, which is not desirable.

My understanding is, Spring provides a ReflectionUtils method for that:

ReflectionUtils.doWithFields(Attachment.class, new FieldCallback() {

   @Override
   public void doWith (Field field) throws IllegalArgumentException, IllegalAccessException
   { 
     // ... do action on this field
   }
}

But this iterates over each field in the Attachment object at a time without knowing what the other fields are. Is there a way to get the object I'm working with as a whole?

My task is to set a certain Field to a certain string if another field in this object is NULL. So I have to look at the other fields at the same time.

I'm almost wondering, isn't there a similar method with an Object callback?