B4J Question Received fatal alert: protocol_version

I've tested it with Java 11+ and the latest version of OkHttp, which wasn't yet released in B4J, and it works. You can take it from B4A v10.2 and copy the 4 files to B4J internal libraries folder:
- OkHttp.xml / jar
- okio-1.17.5.jar
- okhttp-3.12.12.jar

BTW, you can use this site to test it: https://tls13.1d.pw/