Fix ReactorReader incorrect warnings and logic (fixes #2497)

[gnodet]

Summary

Fixes #2497 by correcting the ReactorReader logic that was causing incorrect warnings and behavior.

Problem

The ReactorReader was:

1. Comparing class files against POM files instead of JAR files
2. Returning true (up-to-date) when output files were newer than packaged artifacts
3. Showing misleading warnings even when timestamps were equal

Root Cause

The debug output revealed that the comparison was happening against POM files:

• outputFileLastModified = 1750337881113 (Name.class)
• artifactLastModified = 1750335603495 (domain-3.1.4-SNAPSHOT.pom)

This is fundamentally wrong because class files should be compared against JAR files, not POM files.

Solution

1. Fixed return value: Changed return true to return false when output files are newer than packaged artifacts
2. Skip POM artifacts: Added checks to skip up-to-date validation for POM artifacts since comparing class files against POM files doesn't make sense

Changes

• impl/maven-core/src/main/java/org/apache/maven/ReactorReader.java:
  • Line 255: Fixed return value from true to false when files are newer
  • Lines 115-119: Skip up-to-date check for POM artifacts
  • Lines 180: Skip up-to-date check for POM artifacts in findArtifact method

Expected Behavior

• No more incorrect warnings when comparing class files against POM files
• Correct behavior for JAR artifacts with proper fallback to output directory
• Proper reactor behavior using most up-to-date artifacts during multi-module builds

Testing

Tested with the reproducer case where class files and POM files had the same timestamp - the incorrect warning no longer appears.

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Pull Request opened by Augment Code with guidance from the PR author