Remove META-INF/INDEX.LIST when repackaging a jar file

META-INF/INDEX.LIST files are pointless in an executable jar and
moving application classes from the root of the jar to
BOOT-INF/classes breaks the index, resulting in an
InvalidJarIndexException being thrown.

This commit updates the Repackager to automatically remove a
META-INF/INDEX.LIST file from a jar file that is being repackaged.

Closes gh-6601

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

@@ -141,7 +141,10 @@ public class JarWriter {
 							jarFile.getInputStream(entry));
 				}
 				EntryWriter entryWriter = new InputStreamEntryWriter(inputStream, true);
-				writeEntry(entryTransformer.transform(entry), entryWriter);
+				JarEntry transformedEntry = entryTransformer.transform(entry);
+				if (transformedEntry != null) {
+					writeEntry(transformedEntry, entryWriter);
+				}
 			}
 			finally {
 				inputStream.close();

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

@@ -337,6 +337,9 @@ public class Repackager {
 
 		@Override
 		public JarEntry transform(JarEntry entry) {
+			if (entry.getName().equals("META-INF/INDEX.LIST")) {
+				return null;
+			}
 			if (entry.getName().startsWith("META-INF/")
 					|| entry.getName().startsWith("BOOT-INF/")) {
 				return entry;

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

@@ -518,6 +518,24 @@ public class RepackagerTests {
 		}
 	}
 
+	@Test
+	public void metaInfIndexListIsRemovedFromRepackagedJar() throws Exception {
+		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
+		this.testJarFile.addFile("META-INF/INDEX.LIST",
+				this.temporaryFolder.newFile("INDEX.LIST"));
+		File source = this.testJarFile.getFile();
+		File dest = this.temporaryFolder.newFile("dest.jar");
+		Repackager repackager = new Repackager(source);
+		repackager.repackage(dest, NO_LIBRARIES);
+		JarFile jarFile = new JarFile(dest);
+		try {
+			assertThat(jarFile.getEntry("META-INF/INDEX.LIST")).isNull();
+		}
+		finally {
+			jarFile.close();
+		}
+	}
+
 	private boolean hasLauncherClasses(File file) throws IOException {
 		return hasEntry(file, "org/springframework/boot/")
 				&& hasEntry(file, "org/springframework/boot/loader/JarLauncher.class");