vscode spring boot language server not starting up

[kdvolder]

I see this in the debug output from vscode:

Activating 'vscode-spring-boot' extension
Found java exe: /usr/lib/jvm/java-11-openjdk-amd64/bin/java
isJavaEightOrHigher => true
Redirecting server logs to /tmp/vscode-boot-ls.log
ERR: Error: Could not find or load main class org.springframework.ide.vscode.boot.app.BootLanguagServerBootApp
Caused by: java.lang.ClassNotFoundException: org.springframework.ide.vscode.boot.app.BootLanguagServerBootApp
ERR: 

None of the functionality is working, no completions, validation etc. This makes sense since the server doesn't seem to be starting up at all.

I don't understand why because as far as I can tell the class does exist inside the unpacked vscode extension folder structure.