static public function isPaymentNetwork($paymentNetwork) {
    return ((string) $paymentNetwork == Connect2PayClient::PAYMENT_NETWORK_SOFORT ||
        (string) $paymentNetwork == Connect2PayClient::PAYMENT_NETWORK_PRZELEWY24 ||
        (string) $paymentNetwork == Connect2PayClient::PAYMENT_NETWORK_IDEAL ||
        (string) $paymentNetwork == Connect2PayClient::PAYMENT_NETWORK_GIROPAY ||
        (string) $paymentNetwork == Connect2PayClient::PAYMENT_NETWORK_EPS ||
        (string) $paymentNetwork == Connect2PayClient::PAYMENT_NETWORK_POLI ||
        (string) $paymentNetwork == Connect2PayClient::PAYMENT_NETWORK_DRAGONPAY ||
        (string) $paymentNetwork == Connect2PayClient::PAYMENT_NETWORK_TRUSTLY);
  }