JDT actions not available

[Werzi2001]

As far as I understand there should be multiple actions (like JDTSetRuntime) available when using jdtls. This is not the case for me (no JDT* actions at all). How is it controlled that these actions can be used?

Background:
I have the problem Can't use Java 17.0.6 and Gradle 6.8.3 to import Gradle project. I tried setting runtimes and it worked for some time but it suddenly stopped working today. I want to try to set the runtime using JDTSetRuntime manually.

Edit:
I found the command lua require('jdtls').set_runtime('JavaSE-11') but that fails as jdtls is not found. I have installed jdtls using Mason.

[Werzi2001]

I think I have seriously messed and mixed up mason, lspconfig, jdtls. I have to check that first.