ci: update workflows to Java 21

[grigala]

Check List:

• Fixes Upgrade workflows from Java 17 to 21 #3187
• Unit tests : NA
• Javadoc with a code example (on API only) : NA
• PR meets the contributing guidelines

Following the contributing guidelines will make it easier for us to review and accept your PR.

[scordio]

@grigala thanks for raising the PR!

I've added more references to #3187 about the Javadoc stylesheet issues we encountered with the past upgrades. Do you plan to take care of it as well?

It's basically about generating the Javadoc locally and checking if anything breaks in the resulting pages. If that's the case, we would need to figure out how to apply the same customizations to the Java 21 base stylesheet (like what I've done in #2621).

[grigala]

@grigala thanks for raising the PR!

I've added more references to #3187 about the Javadoc stylesheet issues we encountered with the past upgrades. Do you plan to take care of it as well?

It's basically about generating the Javadoc locally and checking if anything breaks in the resulting pages. If that's the case, we would need to figure out how to apply the same customizations to the Java 21 base stylesheet (like what I've done in #2621).

Sure we are currently on Hackergarten event we will try to do it.

Can you add me, @martinfrancois @georgebax as assignees?

P.S. Greets from Hackergarten Basel team :)

[martinfrancois]

@grigala thanks for raising the PR!

I've added more references to #3187 about the Javadoc stylesheet issues we encountered with the past upgrades. Do you plan to take care of it as well?

It's basically about generating the Javadoc locally and checking if anything breaks in the resulting pages. If that's the case, we would need to figure out how to apply the same customizations to the Java 21 base stylesheet (like what I've done in #2621).

Unfortunately, you were right, the CSS was broken again in Java 21... But we finally managed to fix it, see the last commit I pushed.

[scordio]

It seems the search results lack highlighting.

Current Javadoc:

With the changes from this PR:

JDK 21 Javadoc:

As a minor point, we might want to remove the bold style from the SEARCH label/hyperlink.

[scordio]

We would like to generate the Javadoc with Java 21 already in 3.25.0 so I'll have a look at the style for the search results.

[scordio]

I noticed only now that the stylesheet went a bit far from the baseline that Java 21 provides so I started again from the base stylesheet in 2715b98 and applied the customizations in fc234d6.

[scordio]

Thanks for your contribution, @grigala, @martinfrancois, and @georgebax!