There should be a dedicated section on the website and in the documentation to mention that we do test Hibernate Search against OpenSearch too and that we aim for full compatibility.

Everywhere we mention the "Elasticsearch", we should instead mention "Elasticsearch/OpenSearch".

We should decide how we will handle separate dialects for OpenSearch... in particular they will use separate version numbers, starting back to 1.0, so the "hibernate.search.backend.version" property will become ambiguous unless the user tells us he's using OpenSearch. Having a separate "backend-opensearch" module, and putting the common code in a "backend-elasticsearch-base" module, would be very inconvenient. Maybe we need a separate property to select the fork; we would call that a “variant”, “flavor”, “brand”, “vendor” or whatever is clearer.