The documentation says "The low-level REST client is subject to the same release cycle as Elasticsearch. Replace the version with the desired client version, first released with 5.0.0-alpha4. There is no relation between the client version and the Elasticsearch version that the client can communicate with. The low-level REST client is compatible with all Elasticsearch versions."
Which suggests that there's no need to update to a new version of the client when upgrading ES from 5.6 -> 6.2. However there is a version 6.2.4 of the low level REST client.
But I can't find a revision history for this client, to help me decide whether I want to upgrade. Can someone point me at it please?