Anoter attempted plugin fix

invenio/plugin/custom_invenio_plugin/__init__.py

@@ -1,12 +1,11 @@
 from flask import redirect
-from flask_menu import current_menu
 
 
 def init_app(app):
     """Initialize application."""
 
     @app.route("/amdmodel")
-    @current_menu.register(".main.amdmodel", "About AM-D-Model")
+    @app.extensions["menu"].root().register(".main.amdmodel", "About AM-D-Model")
     def redirect_to_amdmodel():
         """Redirect to the AM-D-Model website."""
         return redirect("https://am-d-model.eu")