code: public static Date getBuildDate()
    {
      Date result = null;
      try
      {
        DateFormat format = new SimpleDateFormat("yyyy-MM-dd_HH-mm-ss");
        String raw = versionProperties.getProperty("build_date");
        if(raw != null)
        {
          result = format.parse(raw);
        }
      }
      catch (ParseException ex)
      {
        log.debug(null, ex);
      }
      return result;
    }
docs: Get the date when ANNIS was built.
  
  @return Either the date or {@code null} if unknown.