public static function changeKeyCase($data, int $case = null)
    {
        $properties = get_object_vars($data);
        foreach ($properties as &$key) {
            $value = & $data->$key;
            unset($data->$key);
            
            $changeCaseKey = ($case == CASE_UPPER) ? strtoupper($key) : strtolower($key);
            $data->$changeCaseKey = & $value;
        }
        
        return $data;
    }