public function getCountryList($includeInternalCodes = false)
    {
        if ($this->countryList === null) {
            $this->countryList = require __DIR__ . '/../Resources/countries.php';
        }
        if ($this->countryExtraList === null) {
            $this->countryExtraList = require __DIR__ . '/../Resources/countries-extra.php';
        }

        if ($includeInternalCodes) {
            return array_merge($this->countryList, $this->countryExtraList);
        }

        return $this->countryList;
    }