docs: protected String getPropertyValue(String prefix, String postfix) {
      String ret = properties.getProperty(prefix + "." + postfix);
      if (ret != null) {
        // logger.debugFine("Found property: "+prefix + "." +
        // postfix+" for "+prefix);
        return ret;
      }
      int pos = prefix.length();
      while (pos > 0) {
        pos = prefix.lastIndexOf('.', pos - 1);
        if (pos <= 0) {
          break;
        }
        ret = properties.getProperty(prefix.substring(0, pos) + '.' + postfix);
        if (ret != null) {
          // logger.debugFine("Found property: "+prefix.substring(0, pos) + "." +
          // postfix+" for "+prefix);
          return ret;
        }
      }
      ret = properties.getProperty(postfix);
      if (ret != null) {
        // logger.debugFine("Found property: "+postfix+" for "+prefix);
        return ret;
      }
      return null;
    }