public function getSubmitParams($params) {

    $submitParams = array();
    foreach ($this->paramFields as $k => $mandatory) {
      if (isset($params[$k]) && strlen($params[$k]) > 0) {
        $submitParams[$k] = $params[$k];
      }
      elseif ((!isset($params[$k]) || strlen($params[$k]) == 0) && $mandatory) {
        throw new \Exception('mandatory field ' . $k . ' is unset or empty');
      }
    }

    return $submitParams;
  }