Add signing plugin

- Gradle build can now sign artifacts conditionally
- Relates #1033

Author: jvalkeal

buildSrc/src/main/java/org/springframework/shell/gradle/SpringMavenPlugin.java

@@ -21,8 +21,6 @@
 import org.gradle.api.Plugin;
 import org.gradle.api.Project;
 import org.gradle.api.attributes.Usage;
-import org.gradle.api.component.AdhocComponentWithVariants;
-import org.gradle.api.component.ConfigurationVariantDetails;
 import org.gradle.api.plugins.JavaPlugin;
 import org.gradle.api.plugins.JavaPluginExtension;
 import org.gradle.api.plugins.PluginManager;
@@ -45,6 +43,7 @@ public class SpringMavenPlugin implements Plugin<Project> {
 	public void apply(Project project) {
 		PluginManager pluginManager = project.getPluginManager();
 		pluginManager.apply(MavenPublishPlugin.class);
+		pluginManager.apply(SpringSigningPlugin.class);
 		pluginManager.apply(PublishLocalPlugin.class);
 		pluginManager.apply(PublishAllJavaComponentsPlugin.class);
 
@@ -64,35 +63,15 @@ private void customizeMavenPublication(MavenPublication publication, Project pro
 		customizePom(publication.getPom(), project);
 		project.getPlugins().withType(JavaPlugin.class)
 				.all((javaPlugin) -> customizeJavaMavenPublication(publication, project));
-		suppressMavenOptionalFeatureWarnings(publication);
 	}
 
 	private void customizeJavaMavenPublication(MavenPublication publication, Project project) {
-		addMavenOptionalFeature(project);
 		publication.versionMapping((strategy) -> strategy.usage(Usage.JAVA_API, (mappingStrategy) -> mappingStrategy
 				.fromResolutionOf(JavaPlugin.RUNTIME_CLASSPATH_CONFIGURATION_NAME)));
 		publication.versionMapping(
 				(strategy) -> strategy.usage(Usage.JAVA_RUNTIME, VariantVersionMappingStrategy::fromResolutionResult));
 	}
 
-	private void suppressMavenOptionalFeatureWarnings(MavenPublication publication) {
-		publication.suppressPomMetadataWarningsFor("mavenOptionalApiElements");
-		publication.suppressPomMetadataWarningsFor("mavenOptionalRuntimeElements");
-	}
-
-	private void addMavenOptionalFeature(Project project) {
-		JavaPluginExtension extension = project.getExtensions().getByType(JavaPluginExtension.class);
-		extension.registerFeature("mavenOptional",
-				(feature) -> feature.usingSourceSet(extension.getSourceSets().getByName("main")));
-		AdhocComponentWithVariants javaComponent = (AdhocComponentWithVariants) project.getComponents()
-				.findByName("java");
-		if (javaComponent != null) {
-			javaComponent.addVariantsFromConfiguration(
-				project.getConfigurations().findByName("mavenOptionalRuntimeElements"),
-				ConfigurationVariantDetails::mapToOptional);
-		}
-	}
-
 	private void customizePom(MavenPom pom, Project project) {
 		pom.getUrl().set("https://spring.io/projects/spring-shell");
 		pom.getName().set(project.provider(project::getName));

buildSrc/src/main/java/org/springframework/shell/gradle/SpringSigningPlugin.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2016-2019 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.shell.gradle;
+
+import java.util.concurrent.Callable;
+
+import org.gradle.api.Action;
+import org.gradle.api.Plugin;
+import org.gradle.api.Project;
+import org.gradle.api.publish.Publication;
+import org.gradle.api.publish.PublishingExtension;
+import org.gradle.plugins.signing.SigningExtension;
+import org.gradle.plugins.signing.SigningPlugin;
+
+public class SpringSigningPlugin implements Plugin<Project> {
+	@Override
+	public void apply(Project project) {
+		project.getPluginManager().apply(SigningPlugin.class);
+		project.getPlugins().withType(SigningPlugin.class).all(new Action<SigningPlugin>() {
+			@Override
+			public void execute(SigningPlugin signingPlugin) {
+				boolean hasSigningKey = project.hasProperty("signingKey");
+				if (hasSigningKey) {
+					sign(project);
+				}
+			}
+		});
+	}
+
+	private void sign(Project project) {
+		SigningExtension signing = project.getExtensions().findByType(SigningExtension.class);
+		signing.setRequired(new Callable<Boolean>() {
+			@Override
+			public Boolean call() throws Exception {
+				return project.getGradle().getTaskGraph().hasTask("publishArtifacts");
+			}
+		});
+		String signingKeyId = (String) project.findProperty("signingKeyId");
+		String signingKey = (String) project.findProperty("signingKey");
+		String signingPassword = (String) project.findProperty("signingPassword");
+		if (signingKeyId != null) {
+			signing.useInMemoryPgpKeys(signingKeyId, signingKey, signingPassword);
+		} else {
+			signing.useInMemoryPgpKeys(signingKey, signingPassword);
+		}
+		project.getPlugins().withType(PublishAllJavaComponentsPlugin.class)
+				.all(new Action<PublishAllJavaComponentsPlugin>() {
+					@Override
+					public void execute(PublishAllJavaComponentsPlugin publishingPlugin) {
+						PublishingExtension publishing = project.getExtensions().findByType(PublishingExtension.class);
+						Publication maven = publishing.getPublications().getByName("mavenJava");
+						signing.sign(maven);
+					}
+				});
+	}
+}