Add explicit Maven plugin groupId for clarity

rewrite-maven/src/main/java/org/openrewrite/maven/cleanup/ExplicitPluginGroupId.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2023 the original author or authors.
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.openrewrite.maven.cleanup;
+
+import lombok.EqualsAndHashCode;
+import lombok.Value;
+import org.openrewrite.ExecutionContext;
+import org.openrewrite.Recipe;
+import org.openrewrite.TreeVisitor;
+import org.openrewrite.maven.MavenTagInsertionComparator;
+import org.openrewrite.maven.MavenVisitor;
+import org.openrewrite.xml.AddToTagVisitor;
+import org.openrewrite.xml.tree.Xml;
+
+@Value
+@EqualsAndHashCode(callSuper = true)
+public class ExplicitPluginGroupId extends Recipe {
+    @Override
+    public String getDisplayName() {
+        return "Add explicit `groupId` to Maven plugins";
+    }
+
+    @Override
+    public String getDescription() {
+        return "Add the default `<groupId>org.apache.maven.plugins</groupId>` to plugins for clarity.";
+    }
+
+    @Override
+    public TreeVisitor<?, ExecutionContext> getVisitor() {
+        return new MavenVisitor<ExecutionContext>() {
+            @Override
+            public Xml visitTag(Xml.Tag tag, ExecutionContext ctx) {
+                Xml.Tag t = (Xml.Tag) super.visitTag(tag, ctx);
+                if (isPluginTag() && !t.getChild("groupId").isPresent()) {
+                    Xml.Tag groupIdTag = Xml.Tag.build("<groupId>org.apache.maven.plugins</groupId>");
+                    t = (Xml.Tag) new AddToTagVisitor<>(t, groupIdTag, new MavenTagInsertionComparator(t.getChildren()))
+                            .visitNonNull(t, ctx, getCursor().getParentOrThrow());
+                    maybeUpdateModel();
+                }
+                return t;
+            }
+        };
+    }
+}

rewrite-maven/src/main/resources/META-INF/rewrite/maven.yml

@@ -19,6 +19,7 @@ name: org.openrewrite.maven.BestPractices
 displayName: Apache Maven best practices
 description: Applies best practices to Maven POMs.
 recipeList:
+  - org.openrewrite.maven.cleanup.ExplicitPluginGroupId
   - org.openrewrite.maven.cleanup.PrefixlessExpressions
 
 ---

rewrite-maven/src/test/java/org/openrewrite/maven/cleanup/ExplicitPluginGroupIdTest.java

@@ -0,0 +1,123 @@
+/*
+ * Copyright 2023 the original author or authors.
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.openrewrite.maven.cleanup;
+
+import org.junit.jupiter.api.Test;
+import org.openrewrite.DocumentExample;
+import org.openrewrite.Issue;
+import org.openrewrite.test.RecipeSpec;
+import org.openrewrite.test.RewriteTest;
+
+import static org.openrewrite.maven.Assertions.pomXml;
+
+class ExplicitPluginGroupIdTest implements RewriteTest {
+    @Override
+    public void defaults(RecipeSpec spec) {
+        spec.recipe(new ExplicitPluginGroupId());
+    }
+
+    private static final String BEFORE = """
+      <project>
+        <groupId>com.mycompany.app</groupId>
+        <artifactId>my-app</artifactId>
+        <version>1</version>
+        <build>
+          <plugins>
+            <plugin>
+              <artifactId>maven-compiler-plugin</artifactId>
+              <version>3.8.0</version>
+              <configuration>
+                <source>1.8</source>
+                <target>1.8</target>
+              </configuration>
+            </plugin>
+          </plugins>
+        </build>
+      </project>
+      """;
+
+    private static final String AFTER = """
+      <project>
+        <groupId>com.mycompany.app</groupId>
+        <artifactId>my-app</artifactId>
+        <version>1</version>
+        <build>
+          <plugins>
+            <plugin>
+              <groupId>org.apache.maven.plugins</groupId>
+              <artifactId>maven-compiler-plugin</artifactId>
+              <version>3.8.0</version>
+              <configuration>
+                <source>1.8</source>
+                <target>1.8</target>
+              </configuration>
+            </plugin>
+          </plugins>
+        </build>
+      </project>
+      """;
+
+    @Test
+    @DocumentExample
+    @Issue("https://github.com/openrewrite/rewrite/issues/3529")
+    void addGroupId() {
+        rewriteRun(pomXml(BEFORE, AFTER));
+    }
+
+    @Test
+    void noopIfPresent() {
+        rewriteRun(pomXml(AFTER));
+    }
+
+    @Test
+    void reportingPlugin() {
+        rewriteRun(
+          pomXml(
+            """
+              <project>
+                <groupId>com.mycompany.app</groupId>
+                <artifactId>my-app</artifactId>
+                <version>1</version>
+                <reporting>
+                  <plugins>
+                    <plugin>
+                      <artifactId>maven-project-info-reports-plugin</artifactId>
+                      <version>2.6</version>
+                    </plugin>
+                  </plugins>
+                </reporting>
+              </project>
+              """,
+            """
+              <project>
+                <groupId>com.mycompany.app</groupId>
+                <artifactId>my-app</artifactId>
+                <version>1</version>
+                <reporting>
+                  <plugins>
+                    <plugin>
+                      <groupId>org.apache.maven.plugins</groupId>
+                      <artifactId>maven-project-info-reports-plugin</artifactId>
+                      <version>2.6</version>
+                    </plugin>
+                  </plugins>
+                </reporting>
+              </project>
+              """
+          )
+        );
+    }
+}

rewrite-maven/src/test/java/org/openrewrite/maven/cleanup/ManagedDependencyRequiresVersionTest.java

@@ -22,7 +22,6 @@
 import static org.openrewrite.maven.Assertions.pomXml;
 
 class ManagedDependencyRequiresVersionTest implements RewriteTest {
-
     @Issue("https://github.com/openrewrite/rewrite/issues/1084")
     @Test
     void dependencyManagementDependencyRequiresVersion() {