Close ClassLoader so jar it references can be deleted on Windows

Polishes 952ac7b8

spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/restart/classloader/RestartClassLoaderTests.java

@@ -20,7 +20,6 @@ import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
-import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.nio.charset.StandardCharsets;
@@ -219,10 +218,10 @@ class RestartClassLoaderTests {
 	}
 
 	@Test
-	void packagePrivateClassLoadedByParentClassLoaderCanBeProxied() throws MalformedURLException {
+	void packagePrivateClassLoadedByParentClassLoaderCanBeProxied() throws IOException {
-		new ApplicationContextRunner()
+		try (RestartClassLoader restartClassLoader = new RestartClassLoader(ExampleTransactional.class.getClassLoader(),
-				.withClassLoader(new RestartClassLoader(ExampleTransactional.class.getClassLoader(),
+				new URL[] { this.sampleJarFile.toURI().toURL() }, this.updatedFiles)) {
-						new URL[] { this.sampleJarFile.toURI().toURL() }, this.updatedFiles))
+			new ApplicationContextRunner().withClassLoader(restartClassLoader)
 					.withUserConfiguration(ProxyConfiguration.class).run((context) -> {
 						assertThat(context).hasNotFailed();
 						ExampleTransactional transactional = context.getBean(ExampleTransactional.class);
@@ -231,6 +230,7 @@ class RestartClassLoaderTests {
 								.isEqualTo(ExampleTransactional.class.getClassLoader());
 					});
 		}
+	}
 
 	private String readString(InputStream in) throws IOException {
 		return new String(FileCopyUtils.copyToByteArray(in));