Amazon rarely, if ever, releases API version changes. They prefer to do everything right the first time around. ListObjectsV2 is a rare exception to this. When did they come out with this new API version?
Not able to find anything out on the docs.
From Document History - Amazon Simple Storage Service:
GET Bucket (List Objects) API revised
The GET Bucket (List Objects) API has been revised. We recommend that you use the new version, GET Bucket (List Objects) version 2.
May 4, 2016