Note starters' and annotation processors' jar type in their manifest

See gh-22203

buildSrc/build.gradle

@@ -38,6 +38,10 @@ checkstyle {
 
 gradlePlugin {
 	plugins {
+		annotationProcessorPlugin {
+			id = "org.springframework.boot.annotation-processor"
+			implementationClass = "org.springframework.boot.build.processors.AnnotationProcessorPlugin"
+		}
 		autoConfigurationPlugin {
 			id = "org.springframework.boot.auto-configuration"
 			implementationClass = "org.springframework.boot.build.autoconfigure.AutoConfigurationPlugin"

buildSrc/src/main/java/org/springframework/boot/build/processors/AnnotationProcessorPlugin.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2019-2020 the original author or authors.
+ *
+ * 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
+ *
+ *      https://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.springframework.boot.build.processors;
+
+import java.util.Map;
+import java.util.TreeMap;
+
+import org.gradle.api.Plugin;
+import org.gradle.api.Project;
+import org.gradle.api.tasks.bundling.Jar;
+
+/**
+ * A {@link Plugin} for an annotation processor project.
+ *
+ * @author Christoph Dreis
+ */
+public class AnnotationProcessorPlugin implements Plugin<Project> {
+
+	private static final String JAR_TYPE = "annotation-processor";
+
+	@Override
+	public void apply(Project project) {
+		project.getTasks().withType(Jar.class, (jar) -> project.afterEvaluate((evaluated) -> {
+			jar.manifest((manifest) -> {
+				Map<String, Object> attributes = new TreeMap<>();
+				attributes.put("Spring-Boot-Jar-Type", JAR_TYPE);
+				manifest.attributes(attributes);
+			});
+		}));
+	}
+
+}

buildSrc/src/main/java/org/springframework/boot/build/starters/StarterPlugin.java

@@ -17,6 +17,8 @@
 package org.springframework.boot.build.starters;
 
 import java.io.File;
+import java.util.Map;
+import java.util.TreeMap;
 
 import org.gradle.api.Plugin;
 import org.gradle.api.Project;
@@ -26,6 +28,7 @@ import org.gradle.api.plugins.JavaBasePlugin;
 import org.gradle.api.plugins.JavaLibraryPlugin;
 import org.gradle.api.plugins.JavaPlugin;
 import org.gradle.api.plugins.PluginContainer;
+import org.gradle.api.tasks.bundling.Jar;
 
 import org.springframework.boot.build.ConventionsPlugin;
 import org.springframework.boot.build.DeployedPlugin;
@@ -40,6 +43,8 @@ import org.springframework.util.StringUtils;
  */
 public class StarterPlugin implements Plugin<Project> {
 
+	private static final String JAR_TYPE = "dependencies-starter";
+
 	@Override
 	public void apply(Project project) {
 		PluginContainer plugins = project.getPlugins();
@@ -57,6 +62,7 @@ public class StarterPlugin implements Plugin<Project> {
 				(artifact) -> artifact.builtBy(starterMetadata));
 		createClasspathConflictsCheck(runtimeClasspath, project);
 		createProhibitedDependenciesCheck(runtimeClasspath, project);
+		configureJarManifest(project);
 	}
 
 	private void createClasspathConflictsCheck(Configuration classpath, Project project) {
@@ -75,4 +81,14 @@ public class StarterPlugin implements Plugin<Project> {
 		project.getTasks().getByName(JavaBasePlugin.CHECK_TASK_NAME).dependsOn(checkClasspathForProhibitedDependencies);
 	}
 
+	private void configureJarManifest(Project project) {
+		project.getTasks().withType(Jar.class, (jar) -> project.afterEvaluate((evaluated) -> {
+			jar.manifest((manifest) -> {
+				Map<String, Object> attributes = new TreeMap<>();
+				attributes.put("Spring-Boot-Jar-Type", JAR_TYPE);
+				manifest.attributes(attributes);
+			});
+		}));
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-autoconfigure-processor/build.gradle

@@ -2,6 +2,7 @@ plugins {
 	id "java-library"
 	id "org.springframework.boot.conventions"
 	id "org.springframework.boot.deployed"
+	id "org.springframework.boot.annotation-processor"
 }
 
 description = "Spring Boot AutoConfigure Annotation Processor"

spring-boot-project/spring-boot-tools/spring-boot-configuration-processor/build.gradle

@@ -2,6 +2,7 @@ plugins {
 	id "java-library"
 	id "org.springframework.boot.conventions"
 	id "org.springframework.boot.deployed"
+	id "org.springframework.boot.annotation-processor"
 }
 
 description = "Spring Boot Configuration Annotation Processor"