code: private void addIfNotVisited(Object object, Class<?> clazz) {
      if (object != null && !visited.containsKey(object)) {
        toVisit.add(object);
        visited.put(object, clazz);
      }
    }
docs: Add this object to be visited if it has not already been visited, or scheduled to be.
  
  @param object The object
  @param clazz The type of the field