Add layout=NONE to packaging tools

spring-boot-tools/spring-boot-gradle-plugin/src/main/groovy/org/springframework/boot/gradle/SpringBootPluginExtension.groovy

@@ -38,7 +38,7 @@ import org.springframework.boot.loader.tools.Layouts
 public class SpringBootPluginExtension {
 
 	static enum LayoutType {
-		JAR(new Layouts.Jar()), WAR(new Layouts.War()), ZIP(new Layouts.Expanded()), DIR(new Layouts.Expanded());
+		JAR(new Layouts.Jar()), WAR(new Layouts.War()), ZIP(new Layouts.Expanded()), DIR(new Layouts.Expanded()), NONE(new Layouts.None());
 		Layout layout;
 		private LayoutType(Layout layout) {
 			this.layout = layout;

spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/Layouts.java

@@ -25,6 +25,7 @@ import java.util.Map;
  * Common {@link Layout}s.
  * 
  * @author Phillip Webb
+ * @author Dave Syer
  */
 public class Layouts {
 
@@ -82,6 +83,17 @@ public class Layouts {
 
 	}
 
+	/**
+	 * Executable expanded archive layout.
+	 */
+	public static class None extends Jar {
+
+		@Override
+		public String getLauncherClassName() {
+			return null;
+		}
+	}
+
 	/**
 	 * Executable WAR layout.
 	 */

spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/Repackager.java

@@ -172,12 +172,18 @@ public class Repackager {
 			startClass = MainClassFinder.findMainClass(source,
 					this.layout.getClassesLocation());
 		}
-		if (startClass == null) {
+		String launcherClassName = this.layout.getLauncherClassName();
-			throw new IllegalStateException("Unable to find main class");
+		if (launcherClassName != null) {
+			manifest.getMainAttributes()
+					.putValue(MAIN_CLASS_ATTRIBUTE, launcherClassName);
+			if (startClass == null) {
+				throw new IllegalStateException("Unable to find main class");
+			}
+			manifest.getMainAttributes().putValue(START_CLASS_ATTRIBUTE, startClass);
+		}
+		else if (startClass != null) {
+			manifest.getMainAttributes().putValue(MAIN_CLASS_ATTRIBUTE, startClass);
 		}
-		manifest.getMainAttributes().putValue(MAIN_CLASS_ATTRIBUTE,
-				this.layout.getLauncherClassName());
-		manifest.getMainAttributes().putValue(START_CLASS_ATTRIBUTE, startClass);
 
 		String bootVersion = getClass().getPackage().getImplementationVersion();
 		manifest.getMainAttributes().putValue(BOOT_VERSION_ATTRIBUTE, bootVersion);

spring-boot-tools/spring-boot-loader-tools/src/test/java/org/springframework/boot/loader/tools/RepackagerTests.java

@@ -138,6 +138,30 @@ public class RepackagerTests {
 		new Repackager(this.testJarFile.getFile()).repackage(NO_LIBRARIES);
 	}
 
+	@Test
+	public void noMainClassAndLayoutIsNone() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		File file = this.testJarFile.getFile();
+		Repackager repackager = new Repackager(file);
+		repackager.setLayout(new Layouts.None());
+		repackager.repackage(file, NO_LIBRARIES);
+		Manifest actualManifest = getManifest(file);
+		assertThat(actualManifest.getMainAttributes().getValue("Main-Class"),
+				equalTo("a.b.C"));
+	}
+
+	@Test
+	public void noMainClassAndLayoutIsNoneWithNoMain() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithoutMainMethod.class);
+		File file = this.testJarFile.getFile();
+		Repackager repackager = new Repackager(file);
+		repackager.setLayout(new Layouts.None());
+		repackager.repackage(file, NO_LIBRARIES);
+		Manifest actualManifest = getManifest(file);
+		assertThat(actualManifest.getMainAttributes().getValue("Main-Class"),
+				equalTo(null));
+	}
+
 	@Test
 	public void sameSourceAndDestinationWithBackup() throws Exception {
 		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);

spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/RepackageMojo.java

@@ -36,7 +36,9 @@ import org.springframework.boot.loader.tools.Repackager;
 
 /**
  * MOJO that can can be used to repackage existing JAR and WAR archives so that they can
- * be executed from the command line using {@literal java -jar}.
+ * be executed from the command line using {@literal java -jar}. With
+ * <code>layout=NONE</code> can also be used simply to package a JAR with nested
+ * dependencies (and no main class, so not executable).
  * 
  * @author Phillip Webb
  * @author Dave Syer
@@ -84,7 +86,7 @@ public class RepackageMojo extends AbstractMojo {
 	private String mainClass;
 
 	/**
-	 * The layout to use (JAR, WAR, ZIP, DIR) in case it cannot be inferred.
+	 * The layout to use (JAR, WAR, ZIP, DIR, NONE) in case it cannot be inferred.
 	 */
 	@Parameter
 	private LayoutType layout;
@@ -126,7 +128,7 @@ public class RepackageMojo extends AbstractMojo {
 
 	public static enum LayoutType {
 		JAR(new Layouts.Jar()), WAR(new Layouts.War()), ZIP(new Layouts.Expanded()), DIR(
-				new Layouts.Expanded());
+				new Layouts.Expanded()), NONE(new Layouts.None());
 		private Layout layout;
 
 		public Layout layout() {