Questions about Java Versions for %JDBC External Language Server

I have questions about Java Versions needed for setting up a %JDBC External Language Server

I'm trying to start the %JDBC. External Language Server my local instance of IRIS (2023.1.2). I've recently upgraded Java to version 21.0.1 

When starting the External Language Server, I get this error message:

I've downloaded an older version of Java on my system, but didn't install it (e.g., change JAVA_PATH, etc. on O/S).

However, I changed the %JDBC Server configuration to include the path to that "sidecar" java (C:\Java\openjdk-11.0.2_windows-x64_bin\jdk-11.0.2\) in its Class Path and Java Home Directory fields:

With that version, External Language Server works just fine:

The question is: Does anyone know the latest version of Java for which this will work? Other applications on these machines  need Java versions that are later than Java 11.

Thanks