OpenSearch API Compatibility with Elastic Search

Versions (relevant - OpenSearch/Dashboard/Server OS/Browser):
Elastic Search client 7.10.2
Open Search. 2.6.x
OpenSearch JAVA API Client. 2.6.x

Describe the issue:
Is anyone running Java API Client 2.6.x connecting to elastic search 7.10.x? I couldn’t find any documentation regarding the compatibility between these open search client and elastic search cluster.

The reason is we are planning to migrate from ElasticSearch 7.10.2 to OpenSearch 2.6.x
To reduce the interruption on the site, we are using one client to connect to both so we can switch during runtime.

any help is appreciated

There are clients that can talk to any two adjacent major versions (e.g. 7.10 and 1.x, or 1.x and 2.x). However there are API incompatibilites across such a big jump that could cause issues. The main issue is the renaming of “master” to “cluster manager” in the APIs. However, it’s worth giving it a try because most use cases don’t hit the renamed APIs.