Merge pull request #22859 from awanlin/topic/add-config-for-experimentalExtraAllowedOrigins

Added `experimentalExtraAllowedOrigins` to config

.changeset/sour-ligers-hunt.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-auth-backend': patch
+---
+
+Added `experimentalExtraAllowedOrigins` to config

plugins/auth-backend/config.d.ts

@@ -191,5 +191,9 @@ export interface Config {
        */
       backstageTokenExpiration?: HumanDuration;
     };
+    /**
+     * Additional app origins to allow for authenticating
+     */
+    experimentalExtraAllowedOrigins?: string[];
   };
 }