Flutter Pigeon package returns a list of dynamic

I'm trying to use the new (recommended) approach to platform channels Pigeon https://pub.dev/packages/pigeon I'm trying to get a list of items but pigeon doesn't allow for that currently you have to wrap it up in another class see https://github.com/flutter/flutter/issues/66446, but when I do this the list I get is of type dynamic not of the type of the object I want here is my config stripped down for brevity and privacy lol, first my messages.dart file

class Key {
  String displayName;
  String description;
}

class Keys {
  List<VirtualKey> virtualKeys;
}

after running the code generator (again stripped down)

flutter pub run pigeon \
  --input pigeons/messages.dart \
  --dart_out lib/messages.dart \
  --objc_header_out ios/Classes/messages.h \
  --objc_source_out ios/Classes/messages.m \
  --objc_prefix FLT \
  --java_out myApp/pigeon_plugin/Messages.java \
  --java_package myApp.pigeon_plugin"

I have this generated

class Keys {
  List keys;
  // ignore: unused_element
  Map<dynamic, dynamic> _toMap() {
    final Map<dynamic, dynamic> pigeonMap = <dynamic, dynamic>{};
    pigeonMap['keys'] = keys;
    return pigeonMap;
  }
  // ignore: unused_element
  static Keys _fromMap(Map<dynamic, dynamic> pigeonMap) {
    final Keys result = Keys();
    result.keys = pigeonMap['keys'];
    return result;
  }
}

method that returns this class wrapped in an array list (pidgeon issue https://github.com/flutter/flutter/issues/66453) again sorry for any mistakes trying to edit it for privacy concerns

    override fun getKeys(): Messages.Keys {
        return Messages.Keys().apply {
            this.keys = arrayListOf(getAllKeys())
        }
    }

    fun getAllKeys(): List<Key> {
        return KeyManager().allKeys
    }

So given all this it should give me a Keys object which holds a list of Key but instead when I try to use it I get a Keys object with a list of dynamic see image below, is this expected behaviour or is there a way to fix this? many thanks