access-tokenheader that should be used in the next request is returned in the
access-tokenheader of the response to the previous request. The last request in the diagram fails because it tries to use a token that was invalidated by the previous request.
access-tokenheader for the second request with the
access-tokenheader of the first response because the second request will begin before the first one is complete. The server must allow these batches of concurrent requests to share the same auth token. This diagram illustrates how batch requests are identified by the server: