protected function miscellaneous(): array
    {
        return array_filter([
            'X-Content-Type-Options' => $this->config['x-content-type-options'],
            'X-Download-Options' => $this->config['x-download-options'],
            'X-Frame-Options' => $this->config['x-frame-options'],
            'X-Permitted-Cross-Domain-Policies' => $this->config['x-permitted-cross-domain-policies'],
            'X-XSS-Protection' => $this->config['x-xss-protection'],
            'Referrer-Policy' => $this->config['referrer-policy'],
            'Server' => $this->config['server'] ?? '',
        ]);
    }