AWS Amplify: Return tags and/or metadata with Storage.list

I am using AWS Amplify to list the files in an S3 Bucket:

Storage.list('path/', { level: 'private' })
.then(result => {
    // Process Result
})
.catch(err => console.log(err));

result is the standard json containing eTag, key, lastModified and size.

I want to add custom attributes to each file - e.g. a friendly displayName and visibility flag - and to have these attributes returned when i run Storage.list

I can add the attributes as metadata or tags but how can i retrieve them as part of Storage.list?