Disallow records as part of public API

[modmuss50]

Request for comment

Prevent the use of public records in API classes as this has come up a few times in reviews so would like to get some proper feedback on this. Its only a minor thing, but happens enough I think we should enforce it.

Why

• Hard to expand/refactor, e.g removing a component isnt possible
• Adding a component can be error prone as you need to ensure that a suitable consturctor exists
• Often they arent supposed to be constructed by the API consumer
• Not as clear, e.g you cannot write documentation on each method

Alternative

The following example record in an API class

record Data(String example) { }

would become

interface Data {
  String example();
}

and the actual record lives in an impl package:

record DataImpl(String example) implements Data { }

Where it make a lot of sense to use a record e.g ResourceAmount we can opt allow it. If anyone has any thoughts (for or against) please let them be known in this PR.

[Earthcomputer]

You might want to add a custom error message here, as I don't think this will generate failures that are easy to understand if you don't know about the record rule. I don't know much about configuring checkstyle but custom messages seem possible: https://stackoverflow.com/a/18252466

[Earthcomputer]

These MatchXpath checks could have different IDs so that they can be suppressed individually

[modmuss50]

Im not aware of a way to do this

[Earthcomputer]

https://checkstyle.sourceforge.io/config.html#Id

[modmuss50]

I tried that, it doesnt seem to work.

I also cannot get the custom messages to work.

[Earthcomputer]

Oh well, I guess leave it then