Add methods to BootJar for adding content to BOOT-INF

Closes gh-13000

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

@@ -40,6 +40,8 @@ public class BootJar extends Jar implements BootArchive {
 	private final BootArchiveSupport support = new BootArchiveSupport(
 			"org.springframework.boot.loader.JarLauncher", this::resolveZipCompression);
 
+	private final CopySpec bootInf;
+
 	private FileCollection classpath;
 
 	private String mainClassName;
@@ -48,8 +50,10 @@ public class BootJar extends Jar implements BootArchive {
 	 * Creates a new {@code BootJar} task.
 	 */
 	public BootJar() {
-		into("BOOT-INF/classes", classpathFiles(File::isDirectory));
-		into("BOOT-INF/lib", classpathFiles(File::isFile));
+		this.bootInf = getProject().copySpec().into("BOOT-INF");
+		getMainSpec().with(this.bootInf);
+		this.bootInf.into("classes", classpathFiles(File::isDirectory));
+		this.bootInf.into("lib", classpathFiles(File::isFile));
 	}
 
 	private Action<CopySpec> classpathFiles(Spec<File> filter) {
@@ -128,6 +132,32 @@ public class BootJar extends Jar implements BootArchive {
 		this.support.setExcludeDevtools(excludeDevtools);
 	}
 
+	/**
+	 * Returns a {@code CopySpec} that can be used to add content to the {@code BOOT-INF}
+	 * directory of the jar.
+	 * @return a {@code CopySpec} for {@code BOOT-INF}
+	 * @since 2.0.3
+	 */
+	public CopySpec getBootInf() {
+		CopySpec child = getProject().copySpec();
+		this.bootInf.with(child);
+		return child;
+	}
+
+	/**
+	 * Calls the given {@code action} to add content to the {@code BOOT-INF} directory of
+	 * the jar.
+	 * @param action the {@code Action} to call
+	 * @return the {@code CopySpec} for {@code BOOT-INF} that was passed to the
+	 * {@code Action}
+	 * @since 2.0.3
+	 */
+	public CopySpec bootInf(Action<CopySpec> action) {
+		CopySpec bootInf = getBootInf();
+		action.execute(bootInf);
+		return bootInf;
+	}
+
 	/**
 	 * Returns the {@link ZipCompression} that should be used when adding the file
 	 * represented by the given {@code details} to the jar.

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/bundling/BootJarTests.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -16,6 +16,14 @@
 
 package org.springframework.boot.gradle.tasks.bundling;
 
+import java.io.File;
+import java.io.IOException;
+import java.util.jar.JarFile;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
 /**
  * Tests for {@link BootJar}.
  *
@@ -28,4 +36,28 @@ public class BootJarTests extends AbstractBootArchiveTests<BootJar> {
 				"BOOT-INF/lib", "BOOT-INF/classes");
 	}
 
+	@Test
+	public void contentCanBeAddedToBootInfUsingCopySpecFromGetter() throws IOException {
+		BootJar bootJar = getTask();
+		bootJar.setMainClassName("com.example.Application");
+		bootJar.getBootInf().into("test")
+				.from(new File("build.gradle").getAbsolutePath());
+		bootJar.execute();
+		try (JarFile jarFile = new JarFile(bootJar.getArchivePath())) {
+			assertThat(jarFile.getJarEntry("BOOT-INF/test/build.gradle")).isNotNull();
+		}
+	}
+
+	@Test
+	public void contentCanBeAddedToBootInfUsingCopySpecAction() throws IOException {
+		BootJar bootJar = getTask();
+		bootJar.setMainClassName("com.example.Application");
+		bootJar.bootInf((copySpec) -> copySpec.into("test")
+				.from(new File("build.gradle").getAbsolutePath()));
+		bootJar.execute();
+		try (JarFile jarFile = new JarFile(bootJar.getArchivePath())) {
+			assertThat(jarFile.getJarEntry("BOOT-INF/test/build.gradle")).isNotNull();
+		}
+	}
+
 }