code: @Override
     public boolean isRetainable()
     {
        if (configurationPersister != null)
        {
           return true;
        }
  
        String strfileUri = param.getValue();
        URL fileURL;
        try
        {
           fileURL = configurationService.getURL(strfileUri);
        }
        catch (Exception e)
        {
           return false;
        }
        return fileURL.getProtocol().equals("file");
     }
docs: /*
  (non-Javadoc)
  @see org.exoplatform.services.jcr.config.RepositoryServiceConfiguration#isRetainable()