@RequiresSession
  public List<PrincipalEntity> findAll() {
    TypedQuery<PrincipalEntity> query = entityManagerProvider.get().createQuery("SELECT principal FROM PrincipalEntity principal", PrincipalEntity.class);
    return daoUtils.selectList(query);
  }
Find all principals.

@return all principals or an empty List
ambari-server/src/main/java/org/apache/ambari/server/orm/dao/PrincipalDAO.java