Switch custom repository to one with JDK 9-friendly SSL certification chain

spring-boot-project/spring-boot-cli/src/test/java/org/springframework/boot/cli/compiler/grape/AetherGrapeEngineTests.java

@@ -141,9 +141,12 @@ public class AetherGrapeEngineTests {
 	public void resolutionWithCustomResolver() {
 		Map<String, Object> args = new HashMap<>();
 		AetherGrapeEngine grapeEngine = this.createGrapeEngine();
-		grapeEngine
-				.addResolver(createResolver("restlet.org", "https://maven.restlet.org"));
-		grapeEngine.grab(args, createDependency("org.restlet", "org.restlet", "1.1.6"));
+		grapeEngine.addResolver(
+				createResolver("spring-releases", "https://repo.spring.io/release"));
+		Map<String, Object> dependency = createDependency("io.spring.docresources",
+				"spring-doc-resources", "0.1.1.RELEASE");
+		dependency.put("ext", "zip");
+		grapeEngine.grab(args, dependency);
 		assertThat(this.groovyClassLoader.getURLs().length).isEqualTo(1);
 	}