@Transactional
  public void removeByPK(Long requestId) {
    remove(findByPK(requestId));
  }
Given a collection of request ids, load the corresponding entities
@param requestIds  the collection of request ids
@param refreshHint {@code true} to hint JPA that the list should be refreshed
@return the list entities. An empty list if the requestIds are not provided
ambari-server/src/main/java/org/apache/ambari/server/orm/dao/RequestDAO.java