protected function validateAttribute($object, $attribute)
    {
        $value = $object->$attribute;

        if ($value) {

            if (!preg_match('/^(us|sa|eu|ap)-(north|south|central)?(east|west)?-[1-9]$/', $value)) {
                $this->addError($object, $attribute, 'Please enter a valid AWS region e.g us-east-1.');
            }
        }
    }