S3 Event Bridge events have null values for VersionId. Is this a bug?

Question

When working with Lambda Functions to handle EventBridge events from an S3 bucket with versioning enabled, I find that the VersionId field of the AWS Event object always shows a null value instead of the true value.

For example, here is the JSON AWSEvent that uses the aws.s3@ObjectDeleted schema. This JSON was the event payload that went to my Lambda Function when I deleted an object from a bucket that had versioning enabled: Note that $.object.versionId is null but when I look in the bucket, I see unique Version ID values for both the original cat pic "BeardCat.jpg" and its delete marker. Also, I found the same problem in the AWSEvent JSON for an aws.s3@ObjectCreated event, too. There should have been a non-null VersionId in the ObjectCreated event and the ObjectDeleted event.

Have I found a bug?

Note: Where you see 'xxxx' or 'XXXXXXXXX' I was simply redacting AWS Account numbers and S3 bucket names for privacy reasons.

```
{
    detail: class ObjectDeleted {
        bucket: class Bucket {
            name: tails-dev-images-xxxx
        }
        object: class Object {
            etag: d41d8cd98f00b204e9800998ecf8427e
            key: BeardCat.jpg
            sequencer: 0061CDD784B140A4CB
            versionId: null
        }
        deletionType: null
        reason: DeleteObject
        requestId: null
        requester: XXXXXXXXX
        sourceIpAddress: null
        version: 0
    }
    detailType: null
    resources: [arn:aws:s3:::tails-dev-images-xxxx]
    id: 82b7602e-a2fe-cffb-67c8-73b4c8753f5f
    source: aws.s3
    time: Thu Dec 30 16:00:04 UTC 2021
    region: us-east-2
    version: 0
    account: XXXXXXXXXX
}
```

Answer

Hi!  Good question.

This is most likely caused by how enabling versioning on objects and deletion works.  When versioning is enabled, a simple DELETE call does not permanently delete the object.  Instead, S3 inserts a delete marker and the marker becomes the current version of the object with a new ID.

When trying to GET an object whose current version is a delete marker, Amazon S3 will behave as though the object has been deleted (even though it has not been erased) and returns a 404 error.

References: 
* https://docs.aws.amazon.com/AmazonS3/latest/userguide/DeletingObjectVersions.html
* https://docs.aws.amazon.com/AmazonS3/latest/userguide/DeleteMarker.html

Answer

Some more info re: the Schema aws.s3@ObjectDeleted. It appears that in the Schema definition, the versionId field is actually called 'version-id'. Maybe there is a disconnect here due to the difference in spelling between 'versionId' and 'version-id'.

Here is the relevant excerpt from the aws.s3@ObjectDeleted schema.

```
"Object": {
        "type": "object",
        "required": ["etag", "key", "sequencer"],
        "properties": {
          "etag": {
            "type": "string"
          },
          "key": {
            "type": "string"
          },
          "sequencer": {
            "type": "string"
          },
          "version-id": {
            "type": "string"
          }
        }
```

S3 Event Bridge events have null values for VersionId. Is this a bug?

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