public function getInjectionVariables() {
        $opts = $this->module->getActingOpts();
        $payload = json_encode($this->getSignInPayload(), JSON_UNESCAPED_SLASHES);
        return [
            'merchantId' => $opts['merchant_id'],
            'ledgerCurrency' => $opts['ledgerCurrency'],
            'sandbox' => $opts['sandbox'],
            'checkoutLanguage' => $opts['checkoutLanguage'],
            'buttonColor' => $opts['buttonColor'],
            'signInConfig' => [
                'payloadJSON' => $payload,
                'signature' => $this->module->getAmazonClient()->generateButtonSignature($payload),
                'publicKeyId' => $opts['public_key_id'],
            ],
        ];
    }