Allow use of snapshot repos to be disabled

Previously, the Ivy-based Grape engine used a system property,
disableSpringSnapshotRepos, to control whether or not Spring's
snapshot and milestone repositories were used for dependency
resolution. This commit adds the same capability to AetherGrapeEngine.

[#59489826]

spring-boot-cli-grape/src/main/java/org/springframework/boot/cli/compiler/AetherGrapeEngine.java

@@ -148,12 +148,18 @@ public class AetherGrapeEngine implements GrapeEngine {
 
 		this.repositorySystemSession = repositorySystemSession;
 
-		this.repositories = Arrays.asList(new RemoteRepository.Builder("central",
-				"default", "http://repo1.maven.org/maven2/").build(),
-				new RemoteRepository.Builder("spring-snapshot", "default",
-						"http://repo.spring.io/snapshot").build(),
-				new RemoteRepository.Builder("spring-milestone", "default",
-						"http://repo.spring.io/milestone").build());
+		List<RemoteRepository> repositories = new ArrayList<RemoteRepository>();
+		repositories.add(new RemoteRepository.Builder("central", "default",
+				"http://repo1.maven.org/maven2/").build());
+
+		if (!Boolean.getBoolean("disableSpringSnapshotRepos")) {
+			repositories.add(new RemoteRepository.Builder("spring-snapshot", "default",
+					"http://repo.spring.io/snapshot").build());
+			repositories.add(new RemoteRepository.Builder("spring-milestone", "default",
+					"http://repo.spring.io/milestone").build());
+		}
+
+		this.repositories = repositories;
 
 		this.artifactDescriptorReader = mavenServiceLocator
 				.getService(ArtifactDescriptorReader.class);

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

@@ -70,6 +70,19 @@ public class AetherGrapeEngineTests {
 		assertEquals(6, customClassLoader.getURLs().length);
 	}
 
+	@Test(expected = DependencyResolutionFailedException.class)
+	public void resolutionWithSnapshotRepositoriesDisabled() {
+		Map<String, Object> args = new HashMap<String, Object>();
+		System.setProperty("disableSpringSnapshotRepos", "true");
+		try {
+			new AetherGrapeEngine(this.groovyClassLoader, null, null, null).grab(args,
+					createDependency("org.springframework", "spring-jdbc", "3.2.0.M1"));
+		}
+		finally {
+			System.clearProperty("disableSpringSnapshotRepos");
+		}
+	}
+
 	private Map<String, Object> createDependency(String group, String module,
 			String version) {
 		Map<String, Object> dependency = new HashMap<String, Object>();

spring-boot-cli/src/test/java/org/springframework/boot/cli/SampleIntegrationTests.java

@@ -49,7 +49,6 @@ public class SampleIntegrationTests {
 	@BeforeClass
 	public static void cleanGrapes() throws Exception {
 		GrapesCleaner.cleanIfNecessary();
-		// System.setProperty("ivy.message.logger.level", "3");
 	}
 
 	@Rule