public function populate() {
        $this->addError(new GenericError(
            self::URL_EMPTY,
            self::URL_EMPTY,
            400,
            'URL parameter is empty',
            __('Please enter the site URL.', 'wcexaap')
        ));
        $this->addError(new GenericError(
            self::URL_INVALID,
            self::URL_INVALID,
            400,
            function ($message) {
                return $message;
            },
            __('Please enter a valid URL.', 'wcexaap')
        ));
    }