code: public PersistenceManager getPersistenceManager() {
          if (persistenceManager == null) {
              try {
                  persistenceManager = getPresentationManager().newPersistenceManager();
              } catch (Exception ex) {
                  getPresentationManager().error(ex);
                  throw new ConnectionNotFoundException();
              }
          }
          return persistenceManager;
      }
docs: Return the persistence manager
  
  @return PersistenceManager