Reinstate permissive alias check

Without the permissive check, unusually named static resources are
inaccessible. The need for this may be due to a Jetty bug. This change
restores the tests to their previous form for now.

See gh-40568

spring-boot-tests/spring-boot-integration-tests/spring-boot-server-tests/spring-boot-server-tests-app/src/main/java/com/example/JettyServerCustomizerConfig.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -20,6 +20,7 @@ import org.eclipse.jetty.http.UriCompliance;
 import org.eclipse.jetty.server.AllowedResourceAliasChecker;
 import org.eclipse.jetty.server.Connector;
 import org.eclipse.jetty.server.HttpConnectionFactory;
+import org.eclipse.jetty.server.handler.ContextHandler;
 
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.web.embedded.jetty.JettyServerCustomizer;
@@ -29,19 +30,23 @@ import org.springframework.context.annotation.Configuration;
 /**
  * {@link JettyServerCustomizer} that:
  * <ul>
+ * <li>Approves all aliases to allow access to unusually named static resources
  * <li>Relaxes URI compliance to allow access to static resources with {@code %} in their file name.
  * </ul>
  *
  * @author Madhura Bhave
  * @author Andy Wilkinson
  */
-@ConditionalOnClass(name = "org.eclipse.jetty.server.Connector")
+@ConditionalOnClass(name = {"org.eclipse.jetty.server.handler.ContextHandler"})
 @Configuration(proxyBeanMethods = false)
 public class JettyServerCustomizerConfig {
 
 	@Bean
 	public JettyServerCustomizer jettyServerCustomizer() {
 		return (server) -> {
+			ContextHandler handler = (ContextHandler) server.getHandler();
+			handler.addAliasCheck((path, resource) -> true);
+
 			for (Connector connector : server.getConnectors()) {
 				connector.getConnectionFactory(HttpConnectionFactory.class).getHttpConfiguration()
 						.setUriCompliance(UriCompliance.LEGACY);