Polish new layered jar support

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/gradle/packaging/boot-jar-layered-custom.gradle

@@ -22,7 +22,7 @@ bootJar {
 			}
 			intoLayer("dependencies")
 		}
-		layerOrder "dependencies", "spring-boot-loader", "snapshot-dependencies", "application"
+		layerOrder = ["dependencies", "spring-boot-loader", "snapshot-dependencies", "application"]
 	}
 }
 // end::layered[]

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/gradle/packaging/boot-jar-layered-custom.gradle.kts

@@ -5,6 +5,10 @@ plugins {
 	id("org.springframework.boot") version "{version}"
 }
 
+tasks.getByName<BootJar>("bootJar") {
+	mainClassName = "com.example.ExampleApplication"
+}
+
 // tag::layered[]
 tasks.getByName<BootJar>("bootJar") {
 	layered {
@@ -18,9 +22,9 @@ tasks.getByName<BootJar>("bootJar") {
 			intoLayer("snapshot-dependencies") {
 				include("*:*:*SNAPSHOT")
 			}
-			intoLayer("dependencies") {
+			intoLayer("dependencies")
 		}
-		layersOrder("dependencies", "spring-boot-loader", "snapshot-dependencies", "application")
+		layerOrder = listOf("dependencies", "spring-boot-loader", "snapshot-dependencies", "application")
 	}
 }
 // end::layered[]

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/gradle/packaging/boot-jar-layered-exclude-tools.gradle

@@ -9,7 +9,7 @@ bootJar {
 
 // tag::layered[]
 bootJar {
-	layers {
+	layered {
 		includeLayerTools = false
 	}
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/gradle/packaging/boot-jar-layered-exclude-tools.gradle.kts

@@ -11,8 +11,8 @@ tasks.getByName<BootJar>("bootJar") {
 
 // tag::layered[]
 tasks.getByName<BootJar>("bootJar") {
-	layers {
-		includeLayerTools = false
+	layered {
+		isIncludeLayerTools = false
 	}
 }
 // end::layered[]

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/bundling/BootJar.java

@@ -20,7 +20,6 @@
 import java.util.Collections;
 import java.util.concurrent.Callable;
 
-import groovy.lang.Closure;
 import org.gradle.api.Action;
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.file.CopySpec;
@@ -33,7 +32,6 @@
 import org.gradle.api.tasks.Nested;
 import org.gradle.api.tasks.Optional;
 import org.gradle.api.tasks.bundling.Jar;
-import org.gradle.util.ConfigureUtil;
 
 /**
  * A custom {@link Jar} task that produces a Spring Boot executable jar.
@@ -158,28 +156,33 @@ public void launchScript(Action<LaunchScriptConfiguration> action) {
 		action.execute(enableLaunchScriptIfNecessary());
 	}
 
+	/**
+	 * Returns the spec that describes the layers in a layerd jar.
+	 * @return the spec for the layers or {@code null}.
+	 * @since 2.3.0
+	 */
 	@Nested
 	@Optional
 	public LayeredSpec getLayered() {
 		return this.layered;
 	}
 
+	/**
+	 * Configures the jar to be layered using the default layering.
+	 * @since 2.3.0
+	 */
 	public void layered() {
-		layered(true);
-	}
-
-	public void layered(boolean layered) {
-		this.layered = layered ? new LayeredSpec() : null;
-	}
-
-	public void layered(Closure<?> closure) {
-		layered(ConfigureUtil.configureUsing(closure));
+		enableLayeringIfNecessary();
 	}
 
+	/**
+	 * Configures the jar to be layered, customizing the layers using the given
+	 * {@code action}.
+	 * @param action the action to apply
+	 * @since 2.3.0
+	 */
 	public void layered(Action<LayeredSpec> action) {
-		LayeredSpec layered = new LayeredSpec();
-		action.execute(layered);
-		this.layered = layered;
+		action.execute(enableLayeringIfNecessary());
 	}
 
 	@Override
@@ -258,6 +261,7 @@ protected ZipCompression resolveZipCompression(FileCopyDetails details) {
 	 * {@code BOOT-INF/lib} is considered to be a library.
 	 * @param details the file copy details
 	 * @return {@code true} if the details are for a library
+	 * @since 2.3.0
 	 */
 	protected boolean isLibrary(FileCopyDetails details) {
 		String path = details.getRelativePath().getPathString();
@@ -273,6 +277,13 @@ private LaunchScriptConfiguration enableLaunchScriptIfNecessary() {
 		return launchScript;
 	}
 
+	private LayeredSpec enableLayeringIfNecessary() {
+		if (this.layered == null) {
+			this.layered = new LayeredSpec();
+		}
+		return this.layered;
+	}
+
 	/**
 	 * Syntactic sugar that makes {@link CopySpec#into} calls a little easier to read.
 	 * @param <T> the result type

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/bundling/LayeredSpec.java

@@ -61,59 +61,117 @@ public class LayeredSpec {
 
 	private Layers layers;
 
+	/**
+	 * Returns whether the layer tools should be included as a dependency in the layered
+	 * jar.
+	 * @return whether the layer tools should be included
+	 */
 	@Input
 	public boolean isIncludeLayerTools() {
 		return this.includeLayerTools;
 	}
 
+	/**
+	 * Sets whether the layer tools should be included as a dependency in the layered jar.
+	 * @param includeLayerTools {@code true} if the layer tools should be included,
+	 * otherwise {@code false}
+	 */
 	public void setIncludeLayerTools(boolean includeLayerTools) {
 		this.includeLayerTools = includeLayerTools;
 	}
 
+	/**
+	 * Returns the {@link ApplicationSpec} that controls the layers to which application
+	 * classes and resources belong.
+	 * @return the application spec
+	 */
 	@Input
 	public ApplicationSpec getApplication() {
 		return this.application;
 	}
 
-	public void application(ApplicationSpec spec) {
+	/**
+	 * Sets the {@link ApplicationSpec} that controls the layers to which application
+	 * classes are resources belong.
+	 * @param spec the application spec
+	 */
+	public void setApplication(ApplicationSpec spec) {
 		this.application = spec;
 	}
 
-	public void application(Closure<?> closure) {
-		application(ConfigureUtil.configureUsing(closure));
-	}
-
+	/**
+	 * Customizes the {@link ApplicationSpec} using the given {@code action}.
+	 * @param action the action
+	 */
 	public void application(Action<ApplicationSpec> action) {
 		action.execute(this.application);
 	}
 
+	/**
+	 * Customizes the {@link ApplicationSpec} using the given {@code closure}.
+	 * @param closure the closure
+	 */
+	public void application(Closure<?> closure) {
+		application(ConfigureUtil.configureUsing(closure));
+	}
+
+	/**
+	 * Returns the {@link DependenciesSpec} that controls the layers to which dependencies
+	 * belong.
+	 * @return the dependencies spec
+	 */
 	@Input
 	public DependenciesSpec getDependencies() {
 		return this.dependencies;
 	}
 
-	public void dependencies(DependenciesSpec spec) {
+	/**
+	 * Sets the {@link DependenciesSpec} that controls the layers to which dependencies
+	 * belong.
+	 * @param spec the dependencies spec
+	 */
+	public void setDependencies(DependenciesSpec spec) {
 		this.dependencies = spec;
 	}
 
-	public void dependencies(Closure<?> closure) {
-		dependencies(ConfigureUtil.configureUsing(closure));
-	}
-
+	/**
+	 * Customizes the {@link DependenciesSpec} using the given {@code action}.
+	 * @param action the action
+	 */
 	public void dependencies(Action<DependenciesSpec> action) {
 		action.execute(this.dependencies);
 	}
 
+	/**
+	 * Customizes the {@link DependenciesSpec} using the given {@code closure}.
+	 * @param closure the closure
+	 */
+	public void dependencies(Closure<?> closure) {
+		dependencies(ConfigureUtil.configureUsing(closure));
+	}
+
+	/**
+	 * Returns the order of the layers in the jar from least to most frequently changing.
+	 * @return the layer order
+	 */
 	@Input
 	public List<String> getLayerOrder() {
 		return this.layerOrder;
 	}
 
-	public void layerOrder(String... layerOrder) {
+	/**
+	 * Sets to order of the layers in the jar from least to most frequently changing.
+	 * @param layerOrder the layer order
+	 */
+	public void setLayerOrder(String... layerOrder) {
 		this.layerOrder = Arrays.asList(layerOrder);
 	}
 
-	public void layerOrder(List<String> layerOrder) {
+	/**
+	 * Sets to order of the layers in the jar from least to most frequently changing.
+	 * @param layerOrder the layer order
+	 */
+	public void setLayerOrder(List<String> layerOrder) {
 		this.layerOrder = layerOrder;
 	}
 
@@ -141,6 +199,10 @@ private Layers createLayers() {
 		return new CustomLayers(layers, this.application.asSelectors(), this.dependencies.asSelectors());
 	}
 
+	/**
+	 * Base class for specs that control the layers to which a category of content should
+	 * belong.
+	 */
 	public abstract static class IntoLayersSpec implements Serializable {
 
 		private final List<IntoLayerSpec> intoLayers;
@@ -174,6 +236,9 @@ <T> List<ContentSelector<T>> asSelectors(Function<String, ContentFilter<T>> filt
 
 	}
 
+	/**
+	 * Spec that controls the content that should be part of a particular layer.
+	 */
 	public static class IntoLayerSpec implements Serializable {
 
 		private final String intoLayer;
@@ -182,14 +247,33 @@ public static class IntoLayerSpec implements Serializable {
 
 		private final List<String> excludes = new ArrayList<>();
 
+		/**
+		 * Creates a new {@code IntoLayerSpec} that will control the content of the given
+		 * layer.
+		 * @param intoLayer the layer
+		 */
 		public IntoLayerSpec(String intoLayer) {
 			this.intoLayer = intoLayer;
 		}
 
+		/**
+		 * Adds patterns that control the content that is included in the layer. If no
+		 * includes are specified then all content is included. If includes are specified
+		 * then content must match an inclusion pattern and not match any exclusion
+		 * patterns to be included.
+		 * @param patterns the patterns to be included
+		 */
 		public void include(String... patterns) {
 			this.includes.addAll(Arrays.asList(patterns));
 		}
 
+		/**
+		 * Adds patterns that control the content that is excluded from the layer. If no
+		 * excludes a specified no content is excluded. If exclusions are specified then
+		 * any content that matches an exclusion will be excluded irrespective of whether
+		 * it matches an include pattern.
+		 * @param patterns the patterns to be excluded
+		 */
 		public void exclude(String... patterns) {
 			this.includes.addAll(Arrays.asList(patterns));
 		}
@@ -201,8 +285,17 @@ <T> ContentSelector<T> asSelector(Function<String, ContentFilter<T>> filterFacto
 
 	}
 
+	/**
+	 * An {@link IntoLayersSpec} that controls the layers to which application classes and
+	 * resources belong.
+	 */
 	public static class ApplicationSpec extends IntoLayersSpec {
 
+		/**
+		 * Creates a new {@code ApplicationSpec} with the given {@code contents}.
+		 * @param contents specs for the layers in which application content should be
+		 * included
+		 */
 		public ApplicationSpec(IntoLayerSpec... contents) {
 			super(contents);
 		}
@@ -213,8 +306,15 @@ List<ContentSelector<String>> asSelectors() {
 
 	}
 
+	/**
+	 * An {@link IntoLayersSpec} that controls the layers to which dependencies belong.
+	 */
 	public static class DependenciesSpec extends IntoLayersSpec {
 
+		/**
+		 * Creates a new {@code DependenciesSpec} with the given {@code contents}.
+		 * @param contents specs for the layers in which dependencies should be included
+		 */
 		public DependenciesSpec(IntoLayerSpec... contents) {
 			super(contents);
 		}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/docs/PackagingDocumentationTests.java

@@ -21,6 +21,7 @@
 import java.io.FileReader;
 import java.io.FileWriter;
 import java.io.IOException;
+import java.util.Collections;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
 import java.util.jar.JarOutputStream;
@@ -187,6 +188,36 @@ void bootJarLayered() throws IOException {
 		try (JarFile jar = new JarFile(file)) {
 			JarEntry entry = jar.getJarEntry("BOOT-INF/layers.idx");
 			assertThat(entry).isNotNull();
+			assertThat(Collections.list(jar.entries()).stream().map(JarEntry::getName)
+					.filter((name) -> name.startsWith("BOOT-INF/lib/spring-boot"))).isNotEmpty();
+		}
+	}
+
+	@TestTemplate
+	void bootJarLayeredCustom() throws IOException {
+		this.gradleBuild.script("src/docs/gradle/packaging/boot-jar-layered-custom").build("bootJar");
+		File file = new File(this.gradleBuild.getProjectDir(),
+				"build/libs/" + this.gradleBuild.getProjectDir().getName() + ".jar");
+		assertThat(file).isFile();
+		try (JarFile jar = new JarFile(file)) {
+			JarEntry entry = jar.getJarEntry("BOOT-INF/layers.idx");
+			assertThat(entry).isNotNull();
+			assertThat(Collections.list(jar.entries()).stream().map(JarEntry::getName)
+					.filter((name) -> name.startsWith("BOOT-INF/lib/spring-boot"))).isNotEmpty();
+		}
+	}
+
+	@TestTemplate
+	void bootJarLayeredExcludeTools() throws IOException {
+		this.gradleBuild.script("src/docs/gradle/packaging/boot-jar-layered-exclude-tools").build("bootJar");
+		File file = new File(this.gradleBuild.getProjectDir(),
+				"build/libs/" + this.gradleBuild.getProjectDir().getName() + ".jar");
+		assertThat(file).isFile();
+		try (JarFile jar = new JarFile(file)) {
+			JarEntry entry = jar.getJarEntry("BOOT-INF/layers.idx");
+			assertThat(entry).isNotNull();
+			assertThat(Collections.list(jar.entries()).stream().map(JarEntry::getName)
+					.filter((name) -> name.startsWith("BOOT-INF/lib/spring-boot"))).isEmpty();
 		}
 	}