private function prepareHeaders(&$signature, array $headers = []) 
    {
        $headers["X-Origin"] = self::prepareOrigin();
        $headers["X-Ukey1-App"] = $this->appId;
        $headers["X-Ukey1-Signature"] = $signature;
        
        if ($this->accessToken) {
            $headers["Authorization"] = "Bearer " . $this->accessToken;
        }
        
        return $headers;
    }