[PR] Add IT for dual-API plugin pattern (compile for Maven 3, enhance for Maven 4) [maven]

["gnodet (via GitHub)" <gi...@apache.org>]

gnodet opened a new pull request, #12529:
URL: https://github.com/apache/maven/pull/12529

   ## Summary
   
   Adds an integration test demonstrating the **"compile for 3, enhance for 4"** plugin pattern — a Maven plugin that:
   
   - Compiles against Maven 3.9.x API (`maven-plugin-api`, `maven-core`)
   - Optionally uses Maven 4's typed API (`Session`, `Project`) at runtime
   - Falls back gracefully on Maven 3 — no crashes, no Maven 4 data leaks
   
   ### Architecture
   
   ```
   ProjectInfoMojo.java          ← NO Maven 4 imports (loads on Maven 3)
     │
     │ try { Maven4Enhancer.tryEnhance(...) }
     │ catch (NoClassDefFoundError) { /* Maven 3 path 1 */ }
     │
     ├── Maven4Enhancer.java     ← imports Session, Project (real typed API)
     └── MavenRuntimeDetector.java ← one reflection call for MavenSession.getSession() bridge
   ```
   
   ### Key design points
   
   - **One reflection call**: only `MavenSession.getSession()` uses reflection — it's the bridge method added by Maven 4's compat module that doesn't exist on Maven 3
   - **Everything else is typed**: `session.getMavenVersion()`, `session.getRootDirectory()`, `session.getProjects()`, etc. — direct, compile-time checked
   - **Two Maven 3 fallback paths**:
     1. `NoClassDefFoundError` — Maven 4 API classes absent from classpath
     2. API jar resolved from Central but `getSession()` bridge absent — handled in `tryEnhance()`
   
   ### Verified on both runtimes
   
   | Runtime | `[MVN3]` tags | `[MVN4]` tags | Detection |
   |---------|:-----------:|:-----------:|-----------|
   | Maven 3.9.16 | ✅ all 5 | ✅ none | `[RUNTIME] Maven 3` |
   | Maven 4.1.0-SNAPSHOT | ✅ all 5 | ✅ all 10 | `[RUNTIME] Maven 4` |
   
   ## Test plan
   
   - [x] IT passes on Maven 4 (`mvn verify -Prun-its -Dits.test=MavenITDualApiPluginTest`)
   - [x] Plugin builds and runs correctly on Maven 3.9.16 (manual test)
   - [x] No `[MVN4]` data emitted on Maven 3
   - [x] All `[MVN4]` data emitted on Maven 4
   
   🤖 Generated with [Claude Code](https://claude.com/claude-code)


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Re: [PR] Add IT for dual-API plugin pattern (compile for Maven 3, enhance for Maven 4) [maven]

["gnodet (via GitHub)" <gi...@apache.org>]

gnodet closed pull request #12529: Add IT for dual-API plugin pattern (compile for Maven 3, enhance for Maven 4)
URL: https://github.com/apache/maven/pull/12529


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Re: [PR] Add IT for dual-API plugin pattern (compile for Maven 3, enhance for Maven 4) [maven]

["hboutemy (via GitHub)" <gi...@apache.org>]

hboutemy commented on PR #12529:
URL: https://github.com/apache/maven/pull/12529#issuecomment-5071140835

   great test, could be very useful for improved Java Modules support in a few plugins
   see https://cwiki.apache.org/confluence/spaces/MAVEN/pages/393677487/Full+Java+Modules+Support+-+Current+State#FullJavaModulesSupportCurrentState-ImplementationstrategyforMaven3vsMaven4support 


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