Upgrade to Maven 4.0.0-rc-5 and migrate to public API

[slachiewicz]

Summary

This PR upgrades the project to use Maven 4.0.0-rc-5 and migrates from internal Maven APIs to public APIs where possible, while maintaining backwards compatibility.

Changes

Main Code Changes

1. Xpp3DomBuilder.java

   • Replace org.apache.maven.internal.xml.XmlNodeBuilder with public API org.apache.maven.api.xml.XmlService for cases with trim=true (default behavior)
   • Keep XmlNodeBuilder (internal API) only for trim=false cases to preserve backwards compatibility (XmlService doesn't support trim parameter)
   • Update InputLocationBuilder interface to accept javax.xml.stream.XMLStreamReader instead of XmlPullParser (aligns with Maven 4 public API)

2. XmlPullParserToXMLStreamReaderAdapter.java (new)

   • Create adapter to convert XmlPullParser → XMLStreamReader
   • Enables using existing parsers with new Maven 4 API
   • Implements all required methods including hasName() and hasText()

3. XmlPullParserException.java

   • Remove deprecated detail field (marked @Deprecated)
   • Remove deprecated getDetail() method - use standard getCause() instead

Test Changes

1. Xpp3DomTest.java

   • Update FixedInputLocationBuilder to accept XMLStreamReader instead of XmlPullParser

2. Xpp3DomBuilderTest.java

   • Update anonymous InputLocationBuilder implementation to use XMLStreamReader.getLocation().getLineNumber() instead of XmlPullParser.getLineNumber()

Testing

✅ All 217 tests pass (1 skipped)
✅ Code compiles without errors
✅ Package builds successfully
✅ Uses Maven 4 public API where possible (XmlService for trim=true)
⚠️ Minimal use of internal API only for special cases (trim=false) - required for backwards compatibility

API Usage

• Public: org.apache.maven.api.xml.XmlService, org.apache.maven.api.xml.XmlNode
• Internal (minimal): org.apache.maven.internal.xml.XmlNodeBuilder - only for trim=false
• Internal (existing): org.apache.maven.internal.xml.XmlNodeImpl - used throughout project as wrapper

[slachiewicz]

@gnodet wdyt - make sense this PR?
Do we want to continue with plexus-xml for mvn 4?