ICU-21205 Fix Eclipse failing to import the icu4j maven project

[mihnita]

Checklist

• Required: Issue filed: https://unicode-org.atlassian.net/browse/ICU-21205
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[srl295]

@catamorphism FYI

[jira-pull-request-webhook]

Notice: the branch changed across the force-push!

• icu4j/main/core/pom.xml is now changed in the branch
• icu4j/pom.xml is different

View Diff Across Force-Push

~ Your Friendly Jira-GitHub PR Checker Bot

[mihnita]

I realized something after Steven's approval, and fixed it.
Sorry.

With my previous change ALL the shared test files would be copied in ALL the modules,
because the build-helper-maven-plugin :: add-test-resource was done in the icu4j/pom.xml.

So I changed it to copy only the message2 files in main/core, where they are needed.
Following the same pattern we can later add other shared folders to common_tests, or collate.

---

Does it hurt to copy everything for every module?

Functionally not, these are test files in the *-tests.jar files.

But that is unclean.
And increases the number of files copied around when building, wasting time.

Cons: instead of a lump copy configured in the root pom.xml we would have to add this plugin to each module, with slightly different settings. We have to be more deliberate and think what goes where.

[echeran]

LGTM. Thanks for figuring out the config workaround that IDEs (or at least Eclipse) need to find all of the test resources. Now we a way forward to deduplicate test data across ICU while preserving our tooling support

[mihnita]

or at least Eclipse

I also checked with IntelliJ and VS Code, looks good.
But I don't usually work with these IDEs much (I use VSCode for smaller stuff)
So it might still be possible that certain things don't behave.

But the import and basic build seems fine.