Do not use snapshot repository for dependencyUpdates task

Closes gh-1637

Author: snicoll

gradle/plugins/conventions-plugin/src/main/java/org/springframework/ws/gradle/conventions/JavaBasePluginConventions.java

@@ -29,6 +29,10 @@
  */
 class JavaBasePluginConventions {
 
+	static final String SPRING_MILESTONE_REPOSITORY_NAME = "Spring Milestones";
+
+	static final String SPRING_SNAPSHOT_REPOSITORY_NAME = "Spring Snapshots";
+
 	void apply(Project project) {
 		configureRepositories(project);
 		project.getTasks().withType(Javadoc.class).configureEach((javadoc) -> {
@@ -46,13 +50,13 @@ private void configureRepositories(Project project) {
 		String version = project.getVersion().toString();
 		if (version.contains("-")) {
 			project.getRepositories().maven((repository) -> {
-				repository.setName("Spring Milestones");
+				repository.setName(SPRING_MILESTONE_REPOSITORY_NAME);
 				repository.setUrl("https://repo.spring.io/milestone");
 			});
 		}
 		if (version.endsWith("-SNAPSHOT")) {
 			project.getRepositories().maven((repository) -> {
-				repository.setName("Spring Snapshots");
+				repository.setName(SPRING_SNAPSHOT_REPOSITORY_NAME);
 				repository.setUrl("https://repo.spring.io/snapshot");
 			});
 		}

gradle/plugins/conventions-plugin/src/main/java/org/springframework/ws/gradle/conventions/VersionUpgradePluginConventions.java

@@ -35,6 +35,9 @@ class VersionUpgradePluginConventions {
 	void apply(Project project) {
 		project.getPlugins().apply(VersionsPlugin.class);
 		project.getTasks().withType(DependencyUpdatesTask.class, (updateTask) -> {
+			updateTask.doFirst((task) -> project.getRepositories()
+				.removeIf((candidate) -> candidate.getName()
+					.equals(JavaBasePluginConventions.SPRING_SNAPSHOT_REPOSITORY_NAME)));
 			updateTask.setFilterConfigurations((configuration) -> !(configuration.getName().contains("_")
 					&& configuration.getName().endsWith("+")));
 			VersionUpgradePolicy upgradePolicy = getUpgradePolicy(project);