@RequiresSession
  public MpackEntity findById(long id) {
    return m_entityManagerProvider.get().find(MpackEntity.class, id);
  }
Gets an mpack with the specified ID.

@param id
         the ID of the mpack to retrieve.
@return the mpack or {@code null} if none exists.
ambari-server/src/main/java/org/apache/ambari/server/orm/dao/MpackDAO.java