apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/utils/EntityManagerUtil.java/EntityManagerUtil/closeEntityManager
class EntityManagerUtil:  public void closeEntityManager() {
    EntityManagerHolder emHolder = (EntityManagerHolder)
        TransactionSynchronizationManager.getResource(getEntityManagerFactory());
    if (emHolder == null) {
      return;
    }
    logger.debug("Closing JPA EntityManager in EntityManagerUtil");
    EntityManagerFactoryUtils.closeEntityManager(emHolder.getEntityManager());
  }