Don't duplicate META-INF entries in nested directory jars

Update `ZipContent` so that `META-INF` entries are no longer duplicated
in nested jars created from directory entries. This aligns with the
behavior of the classic loader and prevents the same META-INF file from
being discovered twice.

Fixes gh-38862

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

@@ -637,10 +637,7 @@ public final class ZipContent implements Closeable {
 							.load(zip.data, pos);
 						long namePos = pos + ZipCentralDirectoryFileHeaderRecord.FILE_NAME_OFFSET;
 						short nameLen = centralRecord.fileNameLength();
-						if (ZipString.startsWith(loader.buffer, zip.data, namePos, nameLen, META_INF) != -1) {
-							loader.add(centralRecord, pos, false);
-						}
-						else if (ZipString.startsWith(loader.buffer, zip.data, namePos, nameLen, directoryName) != -1) {
+						if (ZipString.startsWith(loader.buffer, zip.data, namePos, nameLen, directoryName) != -1) {
 							loader.add(centralRecord, pos, true);
 						}
 					}

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

@@ -105,9 +105,8 @@ class NestedJarFileTests {
 	void createWhenNestedJarDirectoryOpensJar() throws IOException {
 		try (NestedJarFile jar = new NestedJarFile(this.file, "d/")) {
 			assertThat(jar.getName()).isEqualTo(this.file.getAbsolutePath() + "!/d/");
-			assertThat(jar.size()).isEqualTo(3);
-			assertThat(jar.stream().map(JarEntry::getName)).containsExactly("META-INF/", "META-INF/MANIFEST.MF",
-					"9.dat");
+			assertThat(jar.size()).isEqualTo(1);
+			assertThat(jar.stream().map(JarEntry::getName)).containsExactly("9.dat");
 		}
 	}
 

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

@@ -210,11 +210,9 @@ class ZipContentTests {
 	@Test
 	void nestedDirectoryReturnsNestedJar() throws IOException {
 		try (ZipContent nested = ZipContent.open(this.file.toPath(), "d/")) {
-			assertThat(nested.size()).isEqualTo(3);
+			assertThat(nested.size()).isEqualTo(1);
 			assertThat(nested.getEntry("9.dat")).isNotNull();
-			assertThat(nested.getEntry(0).getName()).isEqualTo("META-INF/");
-			assertThat(nested.getEntry(1).getName()).isEqualTo("META-INF/MANIFEST.MF");
-			assertThat(nested.getEntry(2).getName()).isEqualTo("9.dat");
+			assertThat(nested.getEntry(0).getName()).isEqualTo("9.dat");
 		}
 	}
 
@@ -230,9 +228,8 @@ class ZipContentTests {
 			File file = new File(this.tempDir, "included.zip");
 			write(file, nested.openRawZipData());
 			try (ZipFile loadedZipFile = new ZipFile(file)) {
-				assertThat(loadedZipFile.size()).isEqualTo(3);
-				assertThat(loadedZipFile.stream().map(ZipEntry::getName)).containsExactly("META-INF/",
-						"META-INF/MANIFEST.MF", "9.dat");
+				assertThat(loadedZipFile.size()).isEqualTo(1);
+				assertThat(loadedZipFile.stream().map(ZipEntry::getName)).containsExactly("9.dat");
 				assertThat(loadedZipFile.getEntry("9.dat")).isNotNull();
 				try (InputStream in = loadedZipFile.getInputStream(loadedZipFile.getEntry("9.dat"))) {
 					ByteArrayOutputStream out = new ByteArrayOutputStream();