For Buster and later Java is being provided in a component/jdk8 for applications relying on Java 8. We don't want to maintain these forward ports indefinitely, so let's check whether WDQS is compatible with Java 11 and switch to it.
(And ideally https://phabricator.wikimedia.org/T264181 is implemented first, since it will make the eventual 8->11 switch as simple as changing one or two lines in Hiera)