Add PkceCodeChallengeMethodEnum

Author: cicnavi

src/Codebooks/PkceCodeChallengeMethodEnum.php

@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\OpenID\Codebooks;
+
+enum PkceCodeChallengeMethodEnum: string
+{
+    case Plain = 'plain';
+
+    case S256 = 'S256';
+}