[maven-4.0.x] Fix incompatible extensions in mvnup for Maven 4

impl/maven-cli/src/main/java/org/apache/maven/cling/invoker/mvnup/goals/AbstractUpgradeGoal.java

@@ -22,10 +22,14 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Map;
 
 import eu.maveniverse.domtrip.Document;
 import eu.maveniverse.domtrip.DomTripException;
+import eu.maveniverse.domtrip.Element;
+import eu.maveniverse.domtrip.Parser;
 import eu.maveniverse.domtrip.maven.MavenPomElements;
 import org.apache.maven.api.cli.mvnup.UpgradeOptions;
 import org.apache.maven.api.di.Inject;
@@ -208,6 +212,9 @@ protected int doUpgrade(UpgradeContext context, String targetModel, Map<Path, Do
             // This is needed for both 4.0.0 and 4.1.0 to help Maven find the project root
             createMvnDirectoryIfNeeded(context);
 
+            // Fix incompatible extensions in .mvn/extensions.xml
+            fixIncompatibleExtensions(context);
+
             return result.errorPoms().isEmpty() ? 0 : 1;
         } catch (Exception e) {
             context.failure("Strategy execution failed: " + e.getMessage());
@@ -272,4 +279,101 @@ protected void createMvnDirectoryIfNeeded(UpgradeContext context) {
             context.failure("Failed to create .mvn directory: " + e.getMessage());
         }
     }
+
+    /**
+     * Fixes incompatible extensions in .mvn/extensions.xml for Maven 4 compatibility.
+     *
+     * <ul>
+     *   <li><strong>os-maven-plugin</strong>: Replaced with Maveniverse Nisse extension
+     *       (compatible with both Maven 3 and 4). Also adds {@code -Dnisse.compat.osDetector}
+     *       to {@code .mvn/maven.config} for drop-in compatibility.</li>
+     *   <li><strong>Develocity/Gradle Enterprise extension</strong>: Removed because it depends
+     *       on {@code org.slf4j.impl.SimpleLogger} which is not available in Maven 4.</li>
+     * </ul>
+     */
+    protected void fixIncompatibleExtensions(UpgradeContext context) {
+        Path startingDirectory = context.options().directory().map(Paths::get).orElse(context.invokerRequest.cwd());
+        Path extensionsXml = startingDirectory.resolve(MVN_DIRECTORY).resolve("extensions.xml");
+
+        if (!Files.exists(extensionsXml)) {
+            return;
+        }
+
+        context.info("");
+        context.info("Checking .mvn/extensions.xml for Maven 4 incompatible extensions...");
+        context.indent();
+
+        try {
+            String content = Files.readString(extensionsXml);
+            Document doc = new Parser().parse(content);
+            Element root = doc.root();
+            boolean modified = false;
+            boolean needsNisseCompat = false;
+
+            List<Element> extensions = root.children("extension").toList();
+            List<Element> toRemove = new ArrayList<>();
+
+            for (Element ext : extensions) {
+                String groupId = ext.childTextTrimmed("groupId");
+                String artifactId = ext.childTextTrimmed("artifactId");
+
+                if ("kr.motd.maven".equals(groupId) && "os-maven-plugin".equals(artifactId)) {
+                    DomUtils.updateOrCreateChildElement(ext, "groupId", "eu.maveniverse.maven.nisse");
+                    DomUtils.updateOrCreateChildElement(ext, "artifactId", "extension");
+                    DomUtils.updateOrCreateChildElement(ext, "version", "0.4.4");
+                    context.detail(
+                            "Replaced kr.motd.maven:os-maven-plugin with eu.maveniverse.maven.nisse:extension:0.4.4");
+                    modified = true;
+                    needsNisseCompat = true;
+                } else if ("com.gradle".equals(groupId)
+                        && ("develocity-maven-extension".equals(artifactId)
+                                || "gradle-enterprise-maven-extension".equals(artifactId))) {
+                    toRemove.add(ext);
+                    context.detail("Removed incompatible extension: " + groupId + ":" + artifactId);
+                    modified = true;
+                }
+            }
+
+            for (Element ext : toRemove) {
+                DomUtils.removeElement(ext);
+            }
+
+            if (modified) {
+                if (shouldSaveModifications()) {
+                    String modifiedXml = DomUtils.toXml(doc);
+                    Files.writeString(extensionsXml, modifiedXml);
+                    context.success("Updated .mvn/extensions.xml");
+
+                    if (needsNisseCompat) {
+                        addNisseCompatFlag(startingDirectory, context);
+                    }
+                } else {
+                    context.action("Would update .mvn/extensions.xml");
+                    if (needsNisseCompat) {
+                        context.action("Would add -Dnisse.compat.osDetector to .mvn/maven.config");
+                    }
+                }
+            } else {
+                context.success("No incompatible extensions found");
+            }
+        } catch (Exception e) {
+            context.failure("Failed to process .mvn/extensions.xml: " + e.getMessage());
+        } finally {
+            context.unindent();
+        }
+    }
+
+    private void addNisseCompatFlag(Path startingDirectory, UpgradeContext context) {
+        Path mavenConfig = startingDirectory.resolve(MVN_DIRECTORY).resolve("maven.config");
+        try {
+            String configContent = Files.exists(mavenConfig) ? Files.readString(mavenConfig) : "";
+            if (!configContent.contains("-Dnisse.compat.osDetector")) {
+                String separator = configContent.isEmpty() || configContent.endsWith("\n") ? "" : "\n";
+                Files.writeString(mavenConfig, configContent + separator + "-Dnisse.compat.osDetector\n");
+                context.success("Added -Dnisse.compat.osDetector to .mvn/maven.config");
+            }
+        } catch (IOException e) {
+            context.failure("Failed to update .mvn/maven.config: " + e.getMessage());
+        }
+    }
 }