Add mapstruct-processor to annotation processor paths when Lombok and MapStruct are used (#1175)

* Add mapstruct-processor to annotation processor paths for Lombok + MapStruct (#1174)

* Use final fields for displayName and description

* Use fluent .actual() in test assertion

* Drop UpgradeToJava17Test full-chain test; covered by AddLombokMapstructBindingTest

Author: timtebeek

src/main/java/org/openrewrite/java/migrate/AddMapstructAnnotationProcessorPath.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2026 the original author or authors.
+ * <p>
+ * Licensed under the Moderne Source Available License (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://docs.moderne.io/licensing/moderne-source-available-license
+ * <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.java.migrate;
+
+import lombok.EqualsAndHashCode;
+import lombok.Value;
+import org.jspecify.annotations.Nullable;
+import org.openrewrite.ExecutionContext;
+import org.openrewrite.ScanningRecipe;
+import org.openrewrite.TreeVisitor;
+import org.openrewrite.maven.AddAnnotationProcessor;
+import org.openrewrite.maven.MavenIsoVisitor;
+import org.openrewrite.maven.tree.ResolvedDependency;
+import org.openrewrite.xml.tree.Xml;
+
+@Value
+@EqualsAndHashCode(callSuper = false)
+public class AddMapstructAnnotationProcessorPath extends ScanningRecipe<AddMapstructAnnotationProcessorPath.Accumulator> {
+
+    private static final String MAPSTRUCT_GROUP = "org.mapstruct";
+    private static final String MAPSTRUCT_ARTIFACT = "mapstruct";
+    private static final String MAPSTRUCT_PROCESSOR_ARTIFACT = "mapstruct-processor";
+
+    String displayName = "Add `mapstruct-processor` to the `maven-compiler-plugin` annotation processor paths";
+
+    String description = "Add the `mapstruct-processor` annotation processor path, matching the version of the `mapstruct` dependency, " +
+            "so that MapStruct mappers are generated when annotation processing is configured explicitly.";
+
+    public static class Accumulator {
+        @Nullable
+        String mapstructVersion;
+        final AddAnnotationProcessor.Scanned processorPaths = new AddAnnotationProcessor.Scanned();
+    }
+
+    @Override
+    public Accumulator getInitialValue(ExecutionContext ctx) {
+        return new Accumulator();
+    }
+
+    @Override
+    public TreeVisitor<?, ExecutionContext> getScanner(Accumulator acc) {
+        // The version is only consulted by the visitor; the scan phase ignores it, so any placeholder is fine here.
+        TreeVisitor<?, ExecutionContext> processorPathScanner =
+                new AddAnnotationProcessor(MAPSTRUCT_GROUP, MAPSTRUCT_PROCESSOR_ARTIFACT, "0").getScanner(acc.processorPaths);
+        return new MavenIsoVisitor<ExecutionContext>() {
+            @Override
+            public Xml.Document visitDocument(Xml.Document document, ExecutionContext ctx) {
+                processorPathScanner.visit(document, ctx);
+                if (acc.mapstructVersion == null) {
+                    for (ResolvedDependency mapstruct : getResolutionResult().findDependencies(MAPSTRUCT_GROUP, MAPSTRUCT_ARTIFACT, null)) {
+                        acc.mapstructVersion = mapstruct.getVersion();
+                        break;
+                    }
+                }
+                return document;
+            }
+        };
+    }
+
+    @Override
+    public TreeVisitor<?, ExecutionContext> getVisitor(Accumulator acc) {
+        if (acc.mapstructVersion == null) {
+            return TreeVisitor.noop();
+        }
+        return new AddAnnotationProcessor(MAPSTRUCT_GROUP, MAPSTRUCT_PROCESSOR_ARTIFACT, acc.mapstructVersion).getVisitor(acc.processorPaths);
+    }
+}

src/main/resources/META-INF/rewrite/java-version-17.yml

@@ -365,6 +365,7 @@ recipeList:
       groupId: org.projectlombok
       artifactId: lombok-mapstruct-binding
       version: 0.2.0
+  - org.openrewrite.java.migrate.AddMapstructAnnotationProcessorPath
 ---
 type: specs.openrewrite.org/v1beta/recipe
 name: org.openrewrite.java.migrate.AddLombokMapstructBindingMavenDependencyOnly