Hi Yoann Rodière

I understand now, this really is a big problem, I think it is a good idea to keep Hibernate Search 6.x with Elasticsearch 6.x compatibility only.

Currently elasticsearch 5.6.x is the current LTS, which is supported until elasticsearch 7.x.x is released.
https://www.elastic.co/support/eol
I believe elasticsearch 6.4.x will be next LTS, maybe Hibernate Search 6 should be concerned about support after this version.

Thanks for the feedback.