[Qerub]

> "LSP tooling" for Java/[…] doesn't exist as far as I'm aware.

There's https://github.com/eclipse/eclipse.jdt.ls. It's used by Visual Studio Code's Language Support for Java (https://marketplace.visualstudio.com/items?itemName=redhat.j...).

[fiddlerwoaroof]

I use this with emacs, and it works pretty well: it was built for Eclipse, but it’s well-integrated into lsp-mode and, more or less, “just works”.

There are also Kotlin and Scala LSP servers that work. The servers themselves can be a bit annoying to get working, but the emacs integration “Just Works”.