JWT support for EL engine calls

[arhamj]

PR Description

Pending

• Generating secret key if not present
• Adding UTs

Others

1. Went with adding caching of the Jwt token
2. Retries on failure is already handled

Fixed Issue(s)

fixes #4958

Documentation

• I thought about documentation and added the documentation label to this PR if updates are required.

Changelog

• I thought about adding a changelog entry, and added one if I deemed necessary.

[ajsutton]

Looking good. The build is failing because error prone wants you to use Instant rather than Date. I was wondering if that would be possible as well because things like time comparison and adding works better with Instant. I'm just not sure if using Instant makes it too hard to work with the jwt library if it's expecting a Date though. If it does we could suppress the warning.

[ajsutton]

Looking good, thanks for your work on this.

[ajsutton]

LGTM. I've pushed up a couple of small changes so that we only add authentication when the kilnv2 ee version is used, and to ensure we get a clear error message if the jwt-secret file can't be read at startup.

Thanks for getting this done, it's really great work.

At this stage I think we're spec compliant and since kilnv2 isn't the default version yet I'm ok with merging it in. The next step will be testing against EL clients that support authentication to ensure it really is compatible and then working through any issue we find.