Upgrade to Elasticsearch 7.17.1

[sothawo]

[linghengqian]

Will there be any timeline to move the default ElasticSearch version to 8.0.1 or 8.1.0?( I refer, of course, to the attributes in pom.xml )

[sothawo]

@linghengqian With Spring Data Elasticsearch version 5. Using Elasticsearch 8 means we have to use the new client because the RestHighlevelClient is not available anymore in 8. But that forces the application to use the jakarta. packages instead of javax. packages because the new client needs that. Spring will change to that with the next version 6, and for Spring Data Elasticsearch that means version 5 then.

Besides that I am still working on integrating the new client from version 7.17.x into Spring Data Elasticsearch as an alternative for Spring Data Elasticsearch 4.4, but there is still work to be done - and there are still bugs in that client.

If you have an Elasticsearch 8 cluster you can set the compatibility headers, but I found and raised an issue for that that form some answer the Elasticsearch 8 cluster returns non compatible answers despite the headers.