Fix Tomcat TldScanner issues by returning raw zip data for nested jars

Update JarUrlConnection so that the full raw zip data is returned from
nested jars when no entry name is specified. This update allows
Tomcat's `WarURLConnection` to work with our nested connections since
they can parse the returned raw zip data.

Fixes gh-38047

spring-boot-project/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/net/protocol/jar/JarUrlConnectionTests.java

@@ -22,6 +22,7 @@ import java.io.FileOutputStream;
 import java.io.FilterInputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.OutputStream;
 import java.net.URL;
 import java.net.URLConnection;
 import java.nio.charset.StandardCharsets;
@@ -237,8 +238,8 @@ class JarUrlConnectionTests {
 	}
 
 	@Test
-	void getInputStreamWhenHasNoEntryThrowsException() throws Exception {
-		JarUrlConnection connection = JarUrlConnection.open(this.url);
+	void getInputStreamWhenNotNestedAndHasNoEntryThrowsException() throws Exception {
+		JarUrlConnection connection = JarUrlConnection.open(JarUrl.create(this.file));
 		assertThatIOException().isThrownBy(() -> connection.getInputStream()).withMessage("no entry name specified");
 	}
 
@@ -271,6 +272,18 @@ class JarUrlConnectionTests {
 			.withMessageContaining("JAR entry missing.dat not found in");
 	}
 
+	@Test // gh-38047
+	void getInputStreamWhenNoEntryAndNestedReturnsFullJarInputStream() throws Exception {
+		JarUrlConnection connection = JarUrlConnection.open(JarUrl.create(this.file, "nested.jar"));
+		File outFile = new File(this.temp, "out.zip");
+		try (OutputStream out = new FileOutputStream(outFile)) {
+			connection.getInputStream().transferTo(out);
+		}
+		try (JarFile outJar = new JarFile(outFile)) {
+			assertThat(outJar.getEntry("3.dat")).isNotNull();
+		}
+	}
+
 	@Test
 	void getInputStreamReturnsInputStream() throws IOException {
 		JarUrlConnection connection = JarUrlConnection.open(JarUrl.create(this.file, "nested.jar", "3.dat"));