Upgrade to Java 21

[yeikel]

Issue submitter TODO list

• [X] I've searched for an already existing issues here
• [X] I'm running a supported version of the application which is listed here and the feature is not present there

Is your proposal related to a problem?

No

Describe the feature you're interested in

As Java 21 is the latest LTS version, I think that we should start testing(and releasing) the project using Java 21

Describe alternatives you've considered

Using Multi-stage builds is an option but it puts me at risk of unknowns as the project is currently tested using Java 17.

Version you're running

2956664

Additional context

We are currently using Java 17

https://github.com/kafbat/kafka-ui/blob/8c7012679d7ec0293e0f96a1740690bf0bfc994e/pom.xml#L21

[Haarolean]

I don't mind, feel free to submit a PR.

[hugomiguelabreu]

@Haarolean, what would be the best approach here? A change with a full upgrade to java 21 or add maven profiles and CI stepa for two releases of jars / containers, one with 21 and another with 17?

[Haarolean]

@hugomiguelabreu the second option is too much overhead, so we're looking for a full upgrade :)