Leave module-info.class in root of archive when repackaging

Closes gh-15810

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -55,13 +55,15 @@ public class BootJar extends Jar implements BootArchive {
 		getMainSpec().with(this.bootInf);
 		this.bootInf.into("classes", classpathFiles(File::isDirectory));
 		this.bootInf.into("lib", classpathFiles(File::isFile));
+		this.bootInf.filesMatching("module-info.class", (details) -> {
+			details.setRelativePath(details.getRelativeSourcePath());
+		});
 	}
 
 	private Action<CopySpec> classpathFiles(Spec<File> filter) {
 		return (copySpec) -> copySpec
 				.from((Callable<Iterable<File>>) () -> (this.classpath != null)
 						? this.classpath.filter(filter) : Collections.emptyList());
-
 	}
 
 	@Override

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -54,6 +54,9 @@ public class BootWar extends War implements BootArchive {
 				(copySpec) -> copySpec.from(
 						(Callable<Iterable<File>>) () -> (this.providedClasspath != null)
 								? this.providedClasspath : Collections.emptyList()));
+		getRootSpec().filesMatching("module-info.class", (details) -> {
+			details.setRelativePath(details.getRelativeSourcePath());
+		});
 	}
 
 	@Override

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -133,6 +133,30 @@ public abstract class AbstractBootArchiveTests<T extends Jar & BootArchive> {
 		}
 	}
 
+	@Test
+	public void moduleInfoClassIsPackagedInTheRootOfTheArchive() throws IOException {
+		this.task.setMainClassName("com.example.Main");
+		File classpathFolder = this.temp.newFolder();
+		File moduleInfoClass = new File(classpathFolder, "module-info.class");
+		moduleInfoClass.getParentFile().mkdirs();
+		moduleInfoClass.createNewFile();
+		File applicationClass = new File(classpathFolder,
+				"com/example/Application.class");
+		applicationClass.getParentFile().mkdirs();
+		applicationClass.createNewFile();
+		this.task.classpath(classpathFolder);
+		this.task.execute();
+		try (JarFile jarFile = new JarFile(this.task.getArchivePath())) {
+			assertThat(
+					jarFile.getEntry(this.classesPath + "/com/example/Application.class"))
+							.isNotNull();
+			assertThat(jarFile.getEntry("com/example/Application.class")).isNull();
+			assertThat(jarFile.getEntry("module-info.class")).isNotNull();
+			assertThat(jarFile.getEntry(this.classesPath + "/module-info.class"))
+					.isNull();
+		}
+	}
+
 	@Test
 	public void classpathCanBeSetUsingAFileCollection() throws IOException {
 		this.task.setMainClassName("com.example.Main");

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -381,7 +381,8 @@ public class Repackager {
 			}
 			if ((entry.getName().startsWith("META-INF/")
 					&& !entry.getName().equals("META-INF/aop.xml"))
-					|| entry.getName().startsWith("BOOT-INF/")) {
+					|| entry.getName().startsWith("BOOT-INF/")
+					|| entry.getName().equals("module-info.class")) {
 				return entry;
 			}
 			JarArchiveEntry renamedEntry = new JarArchiveEntry(

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -661,6 +661,20 @@ public class RepackagerTests {
 		repackager.repackage(dest, NO_LIBRARIES);
 	}
 
+	@Test
+	public void moduleInfoClassRemainsInRootOfJarWhenRepackaged() throws Exception {
+		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
+		this.testJarFile.addClass("module-info.class", ClassWithoutMainMethod.class);
+		File source = this.testJarFile.getFile();
+		File dest = this.temporaryFolder.newFile("dest.jar");
+		Repackager repackager = new Repackager(source);
+		repackager.repackage(dest, NO_LIBRARIES);
+		try (JarFile jarFile = new JarFile(dest)) {
+			assertThat(jarFile.getEntry("module-info.class")).isNotNull();
+			assertThat(jarFile.getEntry("BOOT-INF/classes/module-info.class")).isNull();
+		}
+	}
+
 	private File createLibrary() throws IOException {
 		TestJarFile library = new TestJarFile(this.temporaryFolder);
 		library.addClass("com/example/library/Library.class",