protected static function checkNew(array $data)
    {
        $errors = [];
        if ($missing = array_diff(static::getRequired(), array_keys($data))) {
            $errors[] = 'Missing: ' . implode(', ', $missing);
        }
        foreach ($data as $key => $value) {
            $errors += static::checkProperty($key, $value);
        }
        return $errors;
    }