protected function excludeKeys(array $data) {
        $keys = isset($this->config['excludeKeys']) ? $this->config['excludeKeys'] : [];
        foreach ($data as $key => &$value) {
            if (in_array($key, $keys)) {
                unset($data[$key]);
            } else if (is_array($value)) {
                $value = $this->excludeKeys($value);
            }
        }

        return $data;
    }