fix: mvnup: widen exact Maven version pins to allow Maven 4

[gnodet]

Summary

• Projects like Apache Flink pin their Maven version to an exact version using ranges like [3.8.6,3.8.6] (both bounds equal, both inclusive). The existing MAVEN4_EXCLUSIVE_UPPER_BOUND pattern only matched ranges with an exclusive upper bound at 4.x (e.g. [3.8.8,4)), so exact pins and ranges with an upper bound below 4 were silently skipped.
• Added a new UPPER_BOUND_BELOW_MAVEN4 pattern that catches any version range whose upper bound has a major version less than 4, covering exact version pins ([3.8.6,3.8.6] -> [3.8.6,5)), sub-4 upper bounds ([3.8.0,3.9) -> [3.8.0,5)), and unbounded lower ranges ((,3.9] -> (,5)).
• Added 6 new tests for the new patterns and updated 1 existing test to reflect the corrected behavior for sub-4 upper bounds.

Test plan

• All 27 EnforcerVersionRangeStrategyTest tests pass (was 22 before)
• Exact version pin [3.8.6,3.8.6] is now widened to [3.8.6,5)
• Edge cases tested: [3.0,3.0], [3.9.0,3.9.0], [4.0.0,4.0.0] (not widened)
• Sub-4 upper bound [3.8.8,3.9) is now widened to [3.8.8,5)
• Full POM integration test verifies exact pin widening in plugin configuration
• Existing tests for [3.8.8,4), [3,4), etc. still pass unchanged

🤖 Generated with Claude Code

[gnodet]

Review: mvnup: widen exact Maven version pins to allow Maven 4

Clean fix that closes an important gap in mvnup's EnforcerVersionRangeStrategy — exact version pins like [3.8.6,3.8.6] and sub-4 upper bounds like [3.8.0,3.9) now correctly get widened to allow Maven 4.

What this PR does well

• Correct regex design — UPPER_BOUND_BELOW_MAVEN4 captures the right cases, and the pattern ordering (checking MAVEN4_EXCLUSIVE_UPPER_BOUND first) is essential and well-designed
• Safe fallback — getMajorVersion() returns Integer.MAX_VALUE for unparseable versions, which acts as a "do not widen" guard
• Comprehensive tests — 5 new unit tests + 1 integration test covering exact pins, short versions, and Maven 4 non-widening
• Good Javadoc — the new pattern documents matched/unmatched examples clearly

Suggestions (low priority)

1. [Low] Missing test for unbounded lower bound (,3.9] — the Javadoc lists this as a matched example, but there's no test exercising it. The regex handles it correctly (group 2 captures empty string), but a test would document the behavior.

2. [Low] No test documenting [3.8.8,4] behavior — a range with an inclusive upper bound at exactly 4 is not widened by either pattern (first requires ), second sees major=4 which is not < 4). In Maven semantics [3.8.8,4] includes 4.0.0 but blocks 4.0.1+. The non-widening behavior is reasonable, but a test documenting this decision would be useful.

Checklist

Check	Status
Tests	✓ Comprehensive coverage
Docs	✓ Javadoc updated
Commit convention	✓ fix: prefix
Public API / backward compat	✓ Package-private method
Security	N/A
CI	✓ All 24 checks pass

LGTM.

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Reviewed with Claude Code on behalf of Guillaume Nodet. This review was generated by an AI agent and may contain inaccuracies; please verify all suggestions before applying.