gnodet-bot commented on code in PR #13658:
URL: https://github.com/apache/maven/pull/13658#discussion_r4346478798
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impl/maven-plugin-mixin/src/site/markdown/index.md:
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@@ -0,0 +1,112 @@
+title: Maven Plugin Mixin
+author: Maven Team
+date: ${project.version}
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements. See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership. The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied. See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+# Maven Plugin Mixin
+
+`maven-plugin-mixin` is a mixin for Maven 4 plugin projects. It bundles a JSR
269
+annotation processor that generates Maven 4 plugin descriptors
+(`META-INF/maven/plugin.xml`) and DI factory classes at compile time — with
+**no dependency on `maven-plugin-plugin`** or `maven-plugin-tools`.
+
+## Overview
+
+When you annotate a class with `@org.apache.maven.api.plugin.annotations.Mojo`,
+the processor fires during `javac` and produces:
+
+1. **`META-INF/maven/plugin.xml`** — the plugin descriptor in v2.0.0 format,
+ describing every mojo's goal name, default phase, parameters, dependency
+ resolution requirements, `@After` ordering constraints, and more.
+
+2. **One factory class per mojo** — e.g. `TouchMojo$MojoFactory`, annotated
with
Review Comment:
⚠️ **Stale class name**: the processor generates a top-level class
`TouchMojoMojoFactory` (see `factoryName = simpleName + "MojoFactory"` in
`MojoDescriptorProcessor.java`), but this doc uses `TouchMojo$MojoFactory` —
the `$` notation implies a nested class, which is incorrect.
##########
impl/maven-plugin-mixin/src/test/java/org/apache/maven/plugin/processor/MojoDescriptorProcessorTest.java:
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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.apache.maven.plugin.processor;
+
+import javax.tools.Diagnostic;
+import javax.tools.DiagnosticCollector;
+import javax.tools.FileObject;
+import javax.tools.ForwardingJavaFileManager;
+import javax.tools.JavaCompiler;
+import javax.tools.JavaFileManager;
+import javax.tools.JavaFileObject;
+import javax.tools.SimpleJavaFileObject;
+import javax.tools.StandardJavaFileManager;
+import javax.tools.StandardLocation;
+import javax.tools.ToolProvider;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.StringWriter;
+import java.net.URI;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
+
+/**
+ * Unit tests for {@link MojoDescriptorProcessor} using the JDK in-process
compiler.
+ *
+ * <p>Each test compiles a small in-memory source file that uses the Maven
plugin
+ * annotations ({@code @Mojo}, {@code @Parameter}, etc.) from maven-api-core on
+ * the classpath, with the processor JAR on the processor path. Generated
+ * resources (plugin.xml) and source files (factory classes) are intercepted by
+ * a {@link CapturingFileManager} and asserted in-memory — no disk I/O.</p>
+ */
+class MojoDescriptorProcessorTest {
+
+ /** Resolved classpath jars needed for compiling test sources. */
+ private static List<File> classpathJars;
+
+ /** The processor JAR (contains the compiled MojoDescriptorProcessor). */
+ private static File processorJar;
+
+ @BeforeAll
+ static void resolveClasspath() {
+ // Processor JAR — built from this module
+ processorJar = resolveFile(
+
"impl/maven-plugin-mixin/target/maven-plugin-mixin-4.1.0-SNAPSHOT.jar",
+
"maven-plugin-mixin/4.1.0-SNAPSHOT/maven-plugin-mixin-4.1.0-SNAPSHOT.jar");
+
+ // Annotation JARs needed on the compilation classpath
+ File apiCore = resolveFile(
+ "api/maven-api-core/target/maven-api-core-4.1.0-SNAPSHOT.jar",
+
"maven-api-core/4.1.0-SNAPSHOT/maven-api-core-4.1.0-SNAPSHOT.jar");
+ File apiAnnotations =
+ resolveFile(null,
"maven-api-annotations/4.1.0-SNAPSHOT/maven-api-annotations-4.1.0-SNAPSHOT.jar");
+
+ classpathJars = List.of(apiCore, apiAnnotations);
+ }
+
+ /**
+ * Try to resolve a JAR first from the worktree build output, then from
the local Maven repo.
+ */
+ private static File resolveFile(String worktreeRelative, String
m2Relative) {
+ String worktreeBase =
+ System.getProperty("processor.worktree",
"/opt/data/oss/maven/.worktrees/plugin-processor");
Review Comment:
🐛 **Hardcoded developer path as default**:
`"/opt/data/oss/maven/.worktrees/plugin-processor"` is a machine-specific path.
Any other contributor running the tests will hit this fallback and fail. The
default should be `null` (or omitted), forcing the test to only use the Maven
local repository path (`processor.m2`) which is already portable via
`user.home`.
##########
impl/maven-plugin-mixin/src/main/java/org/apache/maven/plugin/processor/MojoDescriptorProcessor.java:
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@@ -0,0 +1,458 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.apache.maven.plugin.processor;
+
+import javax.annotation.processing.AbstractProcessor;
+import javax.annotation.processing.RoundEnvironment;
+import javax.annotation.processing.SupportedAnnotationTypes;
+import javax.annotation.processing.SupportedOptions;
+import javax.lang.model.SourceVersion;
+import javax.lang.model.element.Element;
+import javax.lang.model.element.ElementKind;
+import javax.lang.model.element.ExecutableElement;
+import javax.lang.model.element.Modifier;
+import javax.lang.model.element.TypeElement;
+import javax.lang.model.element.VariableElement;
+import javax.lang.model.type.DeclaredType;
+import javax.lang.model.type.TypeKind;
+import javax.lang.model.type.TypeMirror;
+import javax.tools.Diagnostic;
+import javax.tools.StandardLocation;
+import javax.xml.stream.XMLStreamException;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.io.Writer;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.function.Consumer;
+
+import org.apache.maven.api.plugin.annotations.After;
+import org.apache.maven.api.plugin.annotations.Execute;
+import org.apache.maven.api.plugin.annotations.Mojo;
+import org.apache.maven.api.plugin.annotations.Resolution;
+import org.apache.maven.api.plugin.descriptor.AfterLink;
+import org.apache.maven.api.plugin.descriptor.MojoDescriptor;
+import org.apache.maven.api.plugin.descriptor.PluginDescriptor;
+import org.apache.maven.plugin.descriptor.io.PluginDescriptorStaxWriter;
+
+/**
+ * JSR 269 annotation processor that generates Maven plugin descriptors
({@code META-INF/maven/plugin.xml})
+ * and DI factory classes at compile time from {@link Mojo @Mojo}-annotated
classes.
+ *
+ * <p>Plugin coordinates are read from compiler {@code -A} options, typically
provided by the
+ * {@code maven-plugin-mixin}.
+ *
+ * @since 4.1.0
+ */
+@SupportedAnnotationTypes("org.apache.maven.api.plugin.annotations.Mojo")
+@SupportedOptions({
+ MojoDescriptorProcessor.OPT_GROUP_ID,
+ MojoDescriptorProcessor.OPT_ARTIFACT_ID,
+ MojoDescriptorProcessor.OPT_VERSION,
+ MojoDescriptorProcessor.OPT_GOAL_PREFIX
+})
+public class MojoDescriptorProcessor extends AbstractProcessor {
+
+ static final String OPT_GROUP_ID = "maven.plugin.groupId";
+ static final String OPT_ARTIFACT_ID = "maven.plugin.artifactId";
+ static final String OPT_VERSION = "maven.plugin.version";
+ static final String OPT_GOAL_PREFIX = "maven.plugin.goalPrefix";
+
+ private final Map<String, TypeElement> mojoElements = new
LinkedHashMap<>();
+ private final Set<String> generatedFactoryNames = new LinkedHashSet<>();
+ private String[] resolvedCoordinates;
+
+ @Override
+ public SourceVersion getSupportedSourceVersion() {
+ return SourceVersion.latestSupported();
+ }
+
+ @Override
+ public boolean process(Set<? extends TypeElement> annotations,
RoundEnvironment roundEnv) {
+ for (TypeElement annotation : annotations) {
+ for (Element element :
roundEnv.getElementsAnnotatedWith(annotation)) {
+ if (!(element instanceof TypeElement typeElement)) {
+ continue;
+ }
+ String fqn = typeElement.getQualifiedName().toString();
+ if (generatedFactoryNames.contains(fqn)) {
+ continue;
+ }
+ if (typeElement.getKind() == ElementKind.INTERFACE) {
+ error("@Mojo must not be placed on an interface", element);
+ continue;
+ }
+ if (typeElement.getModifiers().contains(Modifier.ABSTRACT)) {
+ error("@Mojo must not be placed on an abstract class",
element);
+ continue;
+ }
+ if (!mojoElements.containsKey(fqn)) {
+ mojoElements.put(fqn, typeElement);
+ String[] coords = resolveCoordinates();
+ if (coords != null) {
+ try {
+ generateFactory(typeElement, coords);
+ } catch (IOException e) {
+ error("Failed to generate factory for " + fqn, e);
+ }
+ }
+ }
+ }
+ }
+ if (roundEnv.processingOver() && !mojoElements.isEmpty()) {
+ String[] coords = resolveCoordinates();
+ if (coords != null) {
+ try {
+ writePluginXml(coords);
+ } catch (IOException e) {
+ error("Failed to generate plugin.xml", e);
+ }
+ }
+ }
+ return false;
+ }
+
+ String[] resolveCoordinates() {
+ if (resolvedCoordinates != null) {
+ return resolvedCoordinates;
+ }
+ String groupId = getOption(OPT_GROUP_ID);
+ String artifactId = getOption(OPT_ARTIFACT_ID);
+ String version = getOption(OPT_VERSION);
+ String goalPrefix = getOption(OPT_GOAL_PREFIX);
+ if (isBlank(goalPrefix)) {
+ goalPrefix = deriveGoalPrefix(artifactId);
+ }
+ if (isBlank(groupId) || isBlank(artifactId) || isBlank(version)) {
+ error("Could not determine plugin coordinates. "
+ + "Supply -Amaven.plugin.groupId,
-Amaven.plugin.artifactId and "
+ + "-Amaven.plugin.version via the maven-plugin-mixin.");
+ return null;
+ }
+ resolvedCoordinates = new String[] {groupId, artifactId, version,
goalPrefix};
+ return resolvedCoordinates;
+ }
+
+ private String getOption(String key) {
+ return processingEnv.getOptions().get(key);
+ }
+
+ private void writePluginXml(String[] coords) throws IOException {
+ List<MojoDescriptor> mojos = new ArrayList<>();
+ for (TypeElement mojoType : mojoElements.values()) {
+ MojoDescriptor mojo = buildMojoDescriptor(mojoType);
+ if (mojo != null) {
+ mojos.add(mojo);
+ }
+ }
+ PluginDescriptor descriptor = PluginDescriptor.newBuilder(true)
+ .name(coords[1])
Review Comment:
🐛 **`PluginDescriptor.name` set to artifactId**: `.name(coords[1])` and
`.artifactId(coords[1])` both use the same value. `name` should be a
human-readable label (e.g. the Maven artifact name or goal prefix), not a
duplicate of the artifactId. Consider reading the name from a plugin-level
annotation or at minimum using the goal prefix instead.
##########
impl/maven-plugin-mixin/src/site/markdown/usage.md:
##########
@@ -0,0 +1,122 @@
+title: Usage
+author: Maven Team
+date: ${project.version}
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements. See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership. The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied. See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+# Usage
+
+## Minimal Maven 4 plugin
+
+A complete, functional Maven 4 plugin with one mojo and one `@Parameter`:
+
+```java
+package com.example;
+
+import org.apache.maven.api.plugin.Mojo;
+import org.apache.maven.api.plugin.annotations.Mojo;
+import org.apache.maven.api.plugin.annotations.Parameter;
+
+/**
+ * Prints a greeting.
+ *
+ * @since 1.0.0
+ */
+@Mojo(name = "greet", defaultPhase = "compile")
+public class GreetMojo implements Mojo {
+
+ /**
+ * The name to greet.
+ *
+ * @since 1.0.0
+ */
+ @Parameter(property = "greet.name", defaultValue = "World")
+ private String name;
+
+ @Override
+ public void execute() {
+ System.out.println("Hello, " + name + "!");
+ }
+}
+```
+
+POM configuration (model version 4.2.0, using the mixin):
+
+```xml
+<project xmlns="http://maven.apache.org/POM/4.2.0"; ...>
+
+ <groupId>com.example</groupId>
+ <artifactId>greet-maven-plugin</artifactId>
+ <version>1.0-SNAPSHOT</version>
+ <packaging>jar</packaging>
+
+ <mixins>
+ <mixin>
+ <groupId>org.apache.maven</groupId>
+ <artifactId>maven-plugin-mixin</artifactId>
+ <version>${maven.version}</version>
+ </mixin>
+ </mixins>
+</project>
+```
+
+The mixin configures the compiler plugin automatically — no
+`annotationProcessorPaths` or `-A` options to set up manually.
+
+At compile time, the processor generates:
+
+- `target/classes/META-INF/maven/plugin.xml` — the plugin descriptor
+- `target/generated-sources/annotations/com/example/GreetMojo$MojoFactory.java`
Review Comment:
⚠️ **Stale class name**: same issue — the generated class is
`GreetMojoMojoFactory` (top-level), not `GreetMojo$MojoFactory` (nested).
Update to match the actual output of the processor.
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