ListObjectsResponse.commonPrefixes is always empty

[lionel-rowe]

Given the following response XML (sample response from docs for ListObjectsV2 - Amazon Simple Storage Service):

<?xml version='1.0' encoding='utf-8' ?>
<ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
  <Name>example-bucket</Name>
  <Prefix>photos/2006/</Prefix>
  <Marker></Marker>
  <MaxKeys>1000</MaxKeys>
  <Delimiter>/</Delimiter>
  <IsTruncated>false</IsTruncated>
  <CommonPrefixes>
    <Prefix>photos/2006/February/</Prefix>
  </CommonPrefixes>
  <CommonPrefixes>
    <Prefix>photos/2006/January/</Prefix>
  </CommonPrefixes>
</ListBucketResult>

(await bucket.listObjects(...)).commonPrefixes gives:

[
    { prefix: undefined },
]

Expected:

[
    { prefix: "photos/2006/February/" },
    { prefix: "photos/2006/January/" },
]