ICU-22723 RC API change reports for C/J

[sven-oly]

Checklist

• Required: Issue filed: https://unicode-org.atlassian.net/browse/ICU-22723
• Required: The PR title must be prefixed with a JIRA Issue number.
• Required: The PR description must include the link to the Jira Issue, for example by completing the URL in the first checklist item
• Required: Each commit message must be prefixed with a JIRA Issue number.
• Issue accepted (done by Technical Committee after discussion)
• Tests included, if applicable
• API docs and/or User Guide docs changed or added, if applicable

[markusicu]

@catamorphism @mihnita @echeran There are a lot of MF2 changes here, and below for Java -- both compared with what the API change report showed just a couple of weeks ago. Are these all covered by API proposals?

[catamorphism]

Yes, this is due to #3177 (Java) and #3193 (C++). This removes unsupported expressions/statements from MF2, which includes removing some methods/classes from the data model. I followed Mihai's lead in not submitting a design doc. Should I have submitted one?

[markusicu]

API changes should always be proposed via icu-design email and a section in the API proposal doc.
Even for tech preview, it doesn't make sense to publicly propose the initial API and then silently change parts of it.

[catamorphism]

Got it.

[jira-pull-request-webhook]

Hooray! The files in the branch are the same across the force-push. 😃

~ Your Friendly Jira-GitHub PR Checker Bot

[mihnita]

API changes should always be proposed via icu-design email and a section in the API proposal doc.
Even for tech preview, it doesn't make sense to publicly propose the initial API and then silently change parts of it.

I looked what happened with the previous MF2 Design docs.

The first one is here: https://docs.google.com/document/d/1NkHwFRWV9MiQROq4VVBh21tRMrP2DxpODg3fjHh0-Jw/edit#heading=h.rjgzrdwrcuur

It is called Mf2DataModel and the doc says:

"The data model is still not completely final, but this is the current status.
It is expected to change slightly, mostly based on the feedback we will receive from the users of the tech preview."

The next iteration is here: https://docs.google.com/document/d/1CzzbO5Es-OVMG6OnOMOgJwyU0zn8VlD_LJX3i9kMsuA/edit?resourcekey=0-CLzUfOMJA01jv16aEDj65w#heading=h.gf8wdfvznnx3

"Extensive changes.
At that point we had no data model, it was all “made up” based on the syntax."

And there is only a very high level outline of the data model listing the public classes / interfaces.

The current iteration is 100% identical to that one, except that it removes 3 entries:

static class UnsupportedStatement implements Declaration
static class UnsupportedExpression implements Expression
static class UnsupportedAnnotation implements Annotation

Other than the data model, I checked all classes, and the only differences are the 3 methods above, and the addition of error handling methods (ErrorHandlingBehavior + setter & getter).
Which has an approved design document.

---

I can put together a summary for this release that is very similar to the "second iteration" document before

...
Here is a summary of the APIs changes between the MessageFormat 2 release preview we had in ICU4J 72.1 and the upcoming 75.1 release.

Should I do a 75.1 => 76.1 summary?

[markusicu]

Thanks Mihai for checking!
Ok with me on no proposals for the DataModel.
It's probably useful to include a short section about the tech preview changes and status in the download page, but not a blocker for the release candidate.
@richgillam FYI