fix(gcp): register nested URL protocol handler in GcfJarLauncher

spring-cloud-function-adapters/spring-cloud-function-adapter-gcp/src/main/java/org/springframework/cloud/function/adapter/gcp/GcfJarLauncher.java

@@ -23,13 +23,15 @@
 import com.google.cloud.functions.RawBackgroundFunction;
 
 import org.springframework.boot.loader.launch.JarLauncher;
+import org.springframework.boot.loader.net.protocol.Handlers;
 
 /**
  * The launcher class written at the top-level of the output JAR to be deployed to
  * Google Cloud Functions. This	 is the entry point to the function when run from JAR.
  *
  * @author Ray Tsang
  * @author Daniel Zou
+ * @author Roman Akentev
  */
 public class GcfJarLauncher extends JarLauncher implements HttpFunction, RawBackgroundFunction {
 
@@ -38,7 +40,7 @@ public class GcfJarLauncher extends JarLauncher implements HttpFunction, RawBack
 	private final Object delegate;
 
 	public GcfJarLauncher() throws Exception {
-		//JarFile.registerUrlProtocolHandler();
+		Handlers.register();
 
 		this.loader = createClassLoader(getClassPathUrls());
 

spring-cloud-function-adapters/spring-cloud-function-adapter-gcp/src/test/java/org/springframework/cloud/function/adapter/gcp/GcfJarLauncherTests.java

@@ -0,0 +1,107 @@
+/*
+ * Copyright 2023-present 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.function.adapter.gcp;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests verifying that {@link GcfJarLauncher} registers the {@code nested:}
+ * URL protocol handler via {@code Handlers.register()} before creating its
+ * classloader. Without this, {@code JarUrlClassLoader} would fail with
+ * {@code java.net.MalformedURLException: unknown protocol: nested} when
+ * trying to resolve JARs inside the repackaged archive (GH-1336).
+ * <p>
+ * The test forks a subprocess to avoid interference from other Spring Boot
+ * classes that may have already registered the protocol in the current JVM.
+ *
+ * @author Roman Akentev
+ * @see <a href="https://github.com/spring-cloud/spring-cloud-function/issues/1336">GH-1336</a>
+ */
+public class GcfJarLauncherTests {
+
+	public static final String PROTOCOL_ALREADY_REGISTERED = "PROTOCOL_ALREADY_REGISTERED";
+
+	public static final String PROTOCOL_NOT_REGISTERED = "PROTOCOL_NOT_REGISTERED";
+
+	public static final String GCF_JAR_LAUNCHER_SUCCEEDED = "GCF_JAR_LAUNCHER_SUCCEEDED";
+
+	public static final String GCF_JAR_LAUNCHER_FAILED = "GCF_JAR_LAUNCHER_FAILED";
+
+	public static final String PROTOCOL_NOW_REGISTERED = "PROTOCOL_NOW_REGISTERED";
+
+	public static final String PROTOCOL_STILL_NOT_REGISTERED = "PROTOCOL_STILL_NOT_REGISTERED";
+
+	@TempDir
+	Path tempDir;
+
+	@Test
+	public void nestedProtocolIsRegisteredByGcfJarLauncher() throws Exception {
+		String javaHome = System.getProperty("java.home");
+		String classPath = System.getProperty("java.class.path");
+
+		Path sourceFile = tempDir.resolve("ProtocolCheck.java");
+		try (InputStream in = Objects.requireNonNull(
+				getClass().getResourceAsStream("/ProtocolCheck.java"),
+				"Resource /ProtocolCheck.java not found")) {
+			Files.copy(in, sourceFile, StandardCopyOption.REPLACE_EXISTING);
+		}
+
+		Process compile = new ProcessBuilder(
+				Path.of(javaHome, "bin", "javac").toString(),
+				"-cp", classPath,
+				"-d", tempDir.toString(),
+				sourceFile.toString())
+				.redirectErrorStream(true)
+				.start();
+		String compileOutput = new BufferedReader(
+				new InputStreamReader(compile.getInputStream()))
+				.lines().collect(Collectors.joining("\n"));
+		int compileExit = compile.waitFor();
+		assertThat(compileExit)
+				.as("compilation failed:\n" + compileOutput)
+				.isZero();
+
+		Process run = new ProcessBuilder(
+				Path.of(javaHome, "bin", "java").toString(),
+				"-cp", classPath + File.pathSeparatorChar + tempDir,
+				"ProtocolCheck")
+				.redirectErrorStream(true)
+				.start();
+		String output = new BufferedReader(new InputStreamReader(run.getInputStream()))
+				.lines().collect(Collectors.joining("\n"));
+		int exitCode = run.waitFor();
+
+		assertThat(exitCode).as("ProtocolCheck exit code").isZero();
+		assertThat(output).as("ProtocolCheck output")
+			.contains(PROTOCOL_NOT_REGISTERED + ": unknown protocol: nested")
+			.contains(PROTOCOL_NOW_REGISTERED);
+	}
+
+}

spring-cloud-function-adapters/spring-cloud-function-adapter-gcp/src/test/resources/ProtocolCheck.java

@@ -0,0 +1,39 @@
+import org.springframework.cloud.function.adapter.gcp.GcfJarLauncher;
+import org.springframework.cloud.function.adapter.gcp.GcfJarLauncherTests;
+
+/**
+ * Subprocess entry point for {@link GcfJarLauncherTests}. Compiled and executed
+ * at runtime to verify that the {@code nested:} protocol handler is registered
+ * after {@code GcfJarLauncher} construction (GH-1336).
+ *
+ * @author Roman Akentev
+ */
+public class ProtocolCheck {
+
+	public static void main(String[] args) throws Exception {
+		try {
+			new java.net.URL("nested:/dev/null");
+			System.out.println(GcfJarLauncherTests.PROTOCOL_ALREADY_REGISTERED);
+		}
+		catch (java.net.MalformedURLException e) {
+			System.out.println(GcfJarLauncherTests.PROTOCOL_NOT_REGISTERED + ": " + e.getMessage());
+		}
+		try {
+			new GcfJarLauncher();
+			System.out.println(GcfJarLauncherTests.GCF_JAR_LAUNCHER_SUCCEEDED);
+		}
+		catch (Exception e) {
+			System.out.println(GcfJarLauncherTests.GCF_JAR_LAUNCHER_FAILED + ": "
+					+ e.getClass().getName() + ": " + e.getMessage());
+			e.printStackTrace(System.out);
+		}
+		try {
+			new java.net.URL("nested:/dev/null");
+			System.out.println(GcfJarLauncherTests.PROTOCOL_NOW_REGISTERED);
+		}
+		catch (java.net.MalformedURLException e) {
+			System.out.println(GcfJarLauncherTests.PROTOCOL_STILL_NOT_REGISTERED + ": " + e.getMessage());
+		}
+	}
+
+}