# Type of request: This is a bug report

# Detailed description
S3 list buckets returns a different format for CreationDate than the one expected by the Java SDK and parsing fails. Using Java SDK 2.13.39. Also verified w/ .40, .38, .30 and .20. Will check previous Docker releases for localstack.

``Unable to unmarshall response (Text '2020-06-17T15:26:46.032838+00:00' could not be parsed at index 19). Response Code: 200, Response Text: 
software.amazon.awssdk.core.exception.SdkClientException: Unable to unmarshall response (Text '2020-06-17T15:26:46.032838+00:00' could not be parsed at index 19). Response Code: 200, Response Text: <truncated...>
``

## Expected behavior
Return CreationDate in same format as the actual S3 API call.

## Actual behavior
Returns CreationDate in slightly different format from the actual S3 API call. Fractional seconds are included.

# Steps to reproduce
Run "aws s3api list-buckets" vs "aws s3api list-buckets --endpoint-url http://localstack:4566" and note different date format for CreationDate.

## Command used to start LocalStack
docker-compose:
```
  localstack:
    image: localstack/localstack
    ports:
      - '4566:4566'
    environment:
      SERVICES: s3
      DEBUG: 1
```
## Client code (AWS SDK code snippet, or sequence of "awslocal" commands)
See steps to reproduce.
bucket_name = match.groups()[0]
            break
    
    
    return normalize_bucket_name(bucket_name)
def handle_notification_request(bucket, method, data):
    response = Response()
    response.status_code = 200
    response._content = ''
    if method == 'GET':
        
        result = '<NotificationConfiguration xmlns="%s">' % XMLNS_S3
        if bucket in S3_NOTIFICATIONS:
            notifs = S3_NOTIFICATIONS[bucket]
            for notif in notifs:
                for dest in NOTIFICATION_DESTINATION_TYPES:
                    if dest in notif:
                        dest_dict = {
                            '%sConfiguration' % dest: {
                                'Id': uuid.uuid4(),
                                dest: notif[dest],
                                'Event': notif['Event'],
                                'Filter': notif['Filter']
                            }
                        }
                        result += xmltodict.unparse(dest_dict, full_document=False)
        result += '</NotificationConfiguration>'
        response._content = result
    if method == 'PUT':
        parsed = xmltodict.parse(data)