I've got this to check the JDK version on Mac:

select path 
from (
    select directory as path FROM file
    Where directory = "/Library/Java/JavaVirtualMachines" 
    AND  CAST(SUBSTR(filename, INSTR(filename, '-') +1, (INSTR(filename, '.') - 1) - INSTR(filename, '-')) as INT) >= 9
    union all
    select path from homebrew_packages 
    where name LIKE "%jdk%"
    AND CAST(version as INT) >= 9
);

Which checks for both manual download/install and homebrew installations. Working on getting access to Win/Linux machines with JDK installed so that I can test those as well.

It checks if JDK is installed with a version of 9 or later.