code: public Map.Entry<K, V> getAnchor() {
          Map.Entry<Integer, Map.Entry<K, V>> anchorEntry = anchorList.get(page);
          return anchorEntry == null ? null : anchorEntry.getValue();
      }
docs: Retrieve the anchor object which is the last value object on the previous page.
  <p/>
  Note: This method will return `null` on the first page of the query result.
  
  @return Map.Entry the anchor object which is the last value object on the previous page