Add error message to quarkus-resteasy-reactive-links and improve documentation

[leo-bogastry]

This PR was triggered by the issue #36463

Goal is to clarify the error message the user gets when the class returned by the endpoint does not have and id field and also the documentation about web links

[gsmet]

Thanks. I added a very small comment about the error message.

[github-actions]

🙈 The PR is closed and the preview is expired.

[gsmet]

I added some additional guidance. HTH.

[FroMage]

Added some questions after looking at the code.

[leo-bogastry]

@gsmet @FroMage I'm taking another look at this and I am able to get all the fields and annotations of a class (and then search for the id or @Id) with this code snippet:

private void validateClassHasFieldId(IndexView index, DotName className) {
        List<FieldInfo> allFields = index.getClassByName(className).fields();
        List<AnnotationInstance> allAnnotations = index.getClassByName(className).annotations();
...

but this does not include the fields and annotations a class may inherit from another one.
Is there a way of accessing that? (I was only able to find a getAllKnownSubclasses method an similar)

[leo-bogastry]

@gsmet @FroMage I took another look at this today and I found the information I was missing.
I updated the code to perform a validation before the creation of the web links that searches for fields named id or fields annotated with @Id in the current class and super classes.
In the tests I updated the TestRecord with another level of inheritance and also updated the documentation

[FroMage]

This is much better already, because it moved the validation to build time. There are a few details remaining to fix, but we're almost there :)

[FroMage]

Sorry for the late review, this is getting better but there are still things to tweak.

[FroMage]

So, what happens if we have a superClassName but the superclass is not indexed? No error?

[leo-bogastry]

Indeed, nothing would happen in that scenario. I added a check and exception for this case.

[FroMage]

Well, all comments were resolved, so this is looking good :)

[FroMage]

Review is OK, but can you rebase and remove merge commits please? Then CI will tell us.

[leo-bogastry]

Review is OK, but can you rebase and remove merge commits please? Then CI will tell us.

@FroMage PR all cleaned up 🧹

[FroMage]

Alright, done, thanks a lot for your patience !