On laravel / filament site I have added plugin from https://github.com/parfaitementweb/filament-country-field
and I want use key of countries just as I use in my db in lowercase.

I try to use map as :

                    Country::make('country')->map(function ($countryItems) {
                    //    dd($countryItems); // if to uncomment I see items collection

                    // But I got error on next :
                        foreach ($countryItems   as $key=>$label) {
                            $countryItems[$key] = Str::lower($label);
                        }
                        return $countryItems;
                    }),

raised error :

array_keys(): Argument #1 ($array) must be of type array, Closure given

Which way is correct ?

    "laravel/framework": "^10.48.14",
    "filament/filament": "^3.2-stable",
    "parfaitementweb/filament-country-field": "^2.1"

Thanks in advance!