Tune Maven's own retry/concurrency to reduce Maven Central rate-limiting

[ramakrishnap-nv]

Summary

• java-static-test (from Explore self-contained Java classifier JARs with a statically linked libcuopt #1818) and, less often, java-build have hit 429 Too Many Requests from Maven Central while resolving plugins like maven-source-plugin on a cold repository. cuopt_mvn's retry loop (fixed in Fix cuopt_mvn retry loop being silently skipped under set -e #1823 to actually run under set -e) retries the whole mvn invocation with backoff, but that's compensating for Maven's own resolver never being tuned for CI -- 4 attempts don't reliably outlast a sustained rate-limit window, and by the time the outer wrapper retries, the burst of parallel requests that likely triggered the 429 in the first place repeats.
• cuDF and cuVS already carry a fix for this exact problem in their own Java/Maven builds: a project-level .mvn/maven.config, auto-applied to every mvn invocation with no wrapper script needed, that caps concurrent downloads and adds a real backoff inside Maven's own transport-layer retry handler.

Fix

Add java/cuopt/.mvn/maven.config, matching cuDF's (java/.mvn/maven.config) and cuVS's (java/cuvs-java/.mvn/maven.config) content exactly:

-e
-B
-Daether.connector.basic.downstreamThreads=1
-Daether.transport.http.retryHandler.count=5
-Daether.transport.http.retryHandler.interval=10000
-Dmaven.wagon.http.retryHandler.count=5

• aether.connector.basic.downstreamThreads=1 caps Maven's own concurrent download threads, reducing the burst of parallel requests against Maven Central that likely triggers the rate-limiting in the first place.
• aether.transport.http.retryHandler.interval=10000 adds a real 10s backoff inside Maven's own resolver, at the transport layer.

cuopt_mvn's existing -D flags (java/cuopt/scripts/maven.sh) target the connector-layer retry handler (aether.connector.http.retryHandler.*), which recent Maven resolver versions may no longer consult now that retry logic lives at the transport layer -- this adds the layer that actually gets read. Verified via:

mvn org.apache.maven.plugins:maven-help-plugin:3.4.0:evaluate \
  -Dexpression=aether.transport.http.retryHandler.interval -q -DforceStdout
# -> 10000

cuopt_mvn's outer shell-level retry loop is left in place as a second layer -- it's still useful for failures Maven's own retry can't cover (network drops mid-request, etc).

Test plan

• Confirmed the property resolves correctly via maven-help-plugin:evaluate (see above).
• Ran the full packaged-jar-tests Maven Java suite locally with this config present; passes cleanly.
• java-build and java-static-test CI run clean without hitting Maven Central 429s.

Split out of #1818, where this was found while investigating an unrelated flaky Surefire crash -- this fix is independently useful for the existing java-build job today, not specific to that PR's self-contained classifier JAR work.

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between e2facf8 and af54fa7.

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• java/cuopt/pom.xml

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📝 Walkthrough

Walkthrough

The Java build now runs Maven from java/cuopt, which enables module-local Maven settings. Source and Javadoc JAR attachment runs only when the attach-source-javadoc profile is explicitly activated.

Changes

Maven configuration

Layer / File(s)	Summary
Maven execution and retry settings java/cuopt/.mvn/maven.config, build.sh	The build enters java/cuopt before invoking the relative pom.xml. Maven configuration enables error output, batch mode, one downstream connector thread, five retries, and a 10-second retry interval.
Source and Javadoc attachment profile java/cuopt/pom.xml	The POM places source and Javadoc plugin executions in the attach-source-javadoc profile. Javadoc doclint remains disabled for that profile.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to af54f

The PR only tunes Maven download concurrency and retry backoff; no actionable merge-blocking risk remains after normal checks and review.

Suggested reviewers: iroy30, gforsyth

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description clearly explains the Maven retry, concurrency, and plugin-resolution changes. It also documents verification and pending CI validation.
Title check	✅ Passed	The title is concise, specific, and directly describes the primary Maven retry and concurrency changes intended to reduce Maven Central rate-limiting.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1 files. (1 skipped: 1 unsupported.)

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch java-maven-retry-config

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[github-actions]

CI Test Summary

✅ 21 passed · 10 cancelled / not completed

[ramakrishnap-nv]

/ok to test af54fa7