Add Giropay payment method.

src/Extension.php

@@ -217,6 +217,7 @@ private function get_gateways() {
 				'pronamic_pay_direct_debit_ideal'      => DirectDebitIDealGateway::class,
 				'pronamic_pay_direct_debit_sofort'     => DirectDebitSofortGateway::class,
 				'pronamic_pay_ideal'                   => IDealGateway::class,
+				'pronamic_pay_giropay'                 => GiropayGateway::class,
 				'pronamic_pay_paypal'                  => PayPalGateway::class,
 				'pronamic_pay_sofort'                  => SofortGateway::class,
 			];

src/GiropayGateway.php

@@ -0,0 +1,36 @@
+<?php
+/**
+ * Giropay gateway
+ *
+ * @author    Pronamic <info@pronamic.eu>
+ * @copyright 2005-2023 Pronamic
+ * @license   GPL-3.0-or-later
+ * @package   Pronamic\WordPress\Pay\Extensions\RestrictContentPro
+ */
+
+namespace Pronamic\WordPress\Pay\Extensions\RestrictContentPro;
+
+use Pronamic\WordPress\Pay\Core\PaymentMethods;
+
+/**
+ * Giropay gateway
+ *
+ * @author  Reüel van der Steege
+ * @version 4.4.0
+ * @since   4.4.0
+ */
+class GiropayGateway extends Gateway {
+	/**
+	 * Gateway id.
+	 *
+	 * @var string
+	 */
+	protected $id = 'pronamic_pay_giropay';
+
+	/**
+	 * Payment method.
+	 *
+	 * @var string
+	 */
+	protected $payment_method = PaymentMethods::GIROPAY;
+}