Only add spring-milestones repo for Boot < 4.0

Closes gh-1674

Author: mhalbritter

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/build/SpringBootVersionRepositoriesBuildCustomizer.java

@@ -19,6 +19,8 @@
 import io.spring.initializr.generator.buildsystem.Build;
 import io.spring.initializr.generator.buildsystem.MavenRepository;
 import io.spring.initializr.generator.version.Version;
+import io.spring.initializr.generator.version.VersionParser;
+import io.spring.initializr.generator.version.VersionRange;
 
 /**
  * A {@link BuildCustomizer} that configures the build's repositories based on the version
@@ -41,6 +43,8 @@ class SpringBootVersionRepositoriesBuildCustomizer implements BuildCustomizer<Bu
 		.onlySnapshots()
 		.build();
 
+	private static final VersionRange SPRING_BOOT_4_0_OR_LATER = VersionParser.DEFAULT.parseRange("4.0.0-M1");
+
 	private final Version springBootVersion;
 
 	SpringBootVersionRepositoriesBuildCustomizer(Version springBootVersion) {
@@ -51,13 +55,13 @@ class SpringBootVersionRepositoriesBuildCustomizer implements BuildCustomizer<Bu
 	public void customize(Build build) {
 		build.repositories().add("maven-central");
 		switch (getReleaseType()) {
-			case MILESTONE -> addMilestoneRepository(build);
+			case MILESTONE -> addMilestoneRepositoryIfNeeded(build);
 			case SNAPSHOT -> {
 				if (isMaintenanceRelease()) {
 					addSnapshotRepository(build);
 				}
 				else {
-					addMilestoneRepository(build);
+					addMilestoneRepositoryIfNeeded(build);
 					addSnapshotRepository(build);
 				}
 			}
@@ -89,7 +93,11 @@ private void addSnapshotRepository(Build build) {
 		build.pluginRepositories().add(SPRING_SNAPSHOTS);
 	}
 
-	private void addMilestoneRepository(Build build) {
+	private void addMilestoneRepositoryIfNeeded(Build build) {
+		if (SPRING_BOOT_4_0_OR_LATER.match(this.springBootVersion)) {
+			// Spring Boot 4.0 and up publishes milestones to Maven Central
+			return;
+		}
 		build.repositories().add(SPRING_MILESTONES);
 		build.pluginRepositories().add(SPRING_MILESTONES);
 	}

initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/build/SpringBootVersionRepositoriesBuildCustomizerTests.java

@@ -103,4 +103,19 @@ void maintenanceReleasesShouldNotAddMilestoneRepository() {
 				SpringBootVersionRepositoriesBuildCustomizer.SPRING_SNAPSHOTS);
 	}
 
+	@Test
+	void boot4ReleasesShouldNotAddMilestoneRepository() {
+		MavenBuild build = new MavenBuild();
+		new SpringBootVersionRepositoriesBuildCustomizer(Version.parse("4.0.0-M1")).customize(build);
+		assertThat(build.repositories().items()).containsExactly(MavenRepository.MAVEN_CENTRAL);
+	}
+
+	@Test
+	void boot4SnapshotReleasesShouldNotAddMilestoneRepository() {
+		MavenBuild build = new MavenBuild();
+		new SpringBootVersionRepositoriesBuildCustomizer(Version.parse("4.0.0-SNAPSHOT")).customize(build);
+		assertThat(build.repositories().items()).containsExactly(MavenRepository.MAVEN_CENTRAL,
+				SpringBootVersionRepositoriesBuildCustomizer.SPRING_SNAPSHOTS);
+	}
+
 }