`"_id"`: <document unique id>
`"_index"`: <source index>,
`"_score"`: <relevance score>
`"key"`: <key of the object>,
`"size"`: <size of object in bytes>,
`"user_meta"`: <user metadata from meta= via quilt3>,
`"last_modified"`: <timestamp from ElasticSearch>,
`"updated"`: <object timestamp from S3>,
`"version_id"`: <version_id of object version>
`"_type"`: <document type>