public Map<Object, Long> getTopKFrom(Stat stat, int topK) {
      tryFlushAll();
      return topKeyWrapper.get(stat).topK(topK);
   }
public Map < Object , Long > getTopKFrom ( Stat stat , int topK ) { tryFlushAll ( ) ; return topKeyWrapper . get ( stat ) . topK ( topK ) ; }
@param topK the topK-th first key.
@return the topK-th first key referring to the stat.