Plexus/util writer deprecations

[elharo]

Affected version

HEAD

Bug description

[WARNING] /Users/elharo/maven-build-cache-extension/src/main/java/org/apache/maven/buildcache/checksum/MavenProjectInput.java:[85,38] org.apache.maven.model.io.xpp3.MavenXpp3Writer in org.apache.maven.model.io.xpp3 has been deprecated
[WARNING] /Users/elharo/maven-build-cache-extension/src/main/java/org/apache/maven/buildcache/checksum/MavenProjectInput.java:[87,32] org.codehaus.plexus.util.WriterFactory in org.codehaus.plexus.util has been deprecated
[WARNING] /Users/elharo/maven-build-cache-extension/src/main/java/org/apache/maven/buildcache/checksum/MavenProjectInput.java:[345,30] org.codehaus.plexus.util.WriterFactory in org.codehaus.plexus.util has been deprecated
[WARNING] /Users/elharo/maven-build-cache-extension/src/main/java/org/apache/maven/buildcache/checksum/MavenProjectInput.java:[346,17] org.apache.maven.model.io.xpp3.MavenXpp3Writer in org.apache.maven.model.io.xpp3 has been deprecated

[anukalp2804]

@elharo
I can reproduce these deprecation warnings locally in MavenProjectInput, including the deprecated usage of org.codehaus.plexus.util.WriterFactory.

If it’s acceptable, I’d like to address this incrementally, starting with the WriterFactory usage as a small, self-contained change.