@Override
  public String convert(IAccessEvent accessEvent) {
    if (!isStarted()) {
      return "INACTIVE_REQUEST_PARAM_CONV";
    }

    String[] paramArray = accessEvent.getRequestParameter(key);
    if (paramArray.length == 1) {
      return paramArray[0];
    } else {
      // for an array string {"a", "b"} named 'sa', Array.toString(sa) returns the string
      // "[a, b]".
      return Arrays.toString(paramArray);
    }
  }