Improve Bomr's upgrade suggestions for milestones and RCs

Closes gh-34307

Author: wilkinsona

buildSrc/src/main/java/org/springframework/boot/build/bom/bomr/MavenMetadataVersionResolver.java

@@ -58,7 +58,18 @@ final class MavenMetadataVersionResolver implements VersionResolver {
 
 	MavenMetadataVersionResolver(RestTemplate restTemplate, Collection<URI> repositoryUrls) {
 		this.rest = restTemplate;
-		this.repositoryUrls = repositoryUrls;
+		this.repositoryUrls = normalize(repositoryUrls);
+	}
+
+	private Collection<URI> normalize(Collection<URI> uris) {
+		return uris.stream().map(this::normalize).toList();
+	}
+
+	private URI normalize(URI uri) {
+		if ("/".equals(uri.getPath())) {
+			return uri;
+		}
+		return URI.create(uri.toString() + "/");
 	}
 
 	@Override

buildSrc/src/main/java/org/springframework/boot/build/bom/bomr/version/ArtifactVersionDependencyVersion.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2023 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.
@@ -75,6 +75,20 @@ private boolean isSameMinorAndNewerThan(ArtifactVersionDependencyVersion other)
 				&& isNewerThan(other);
 	}
 
+	@Override
+	public int compareTo(DependencyVersion other) {
+		if (other instanceof ArtifactVersionDependencyVersion otherArtifactDependencyVersion) {
+			ArtifactVersion otherArtifactVersion = otherArtifactDependencyVersion.artifactVersion;
+			if ("snapshot".equalsIgnoreCase(otherArtifactVersion.getQualifier())
+					&& otherArtifactVersion.getMajorVersion() == this.artifactVersion.getMajorVersion()
+					&& otherArtifactVersion.getMinorVersion() == this.artifactVersion.getMinorVersion()
+					&& otherArtifactVersion.getIncrementalVersion() == this.artifactVersion.getIncrementalVersion()) {
+				return 1;
+			}
+		}
+		return super.compareTo(other);
+	}
+
 	@Override
 	public String toString() {
 		return this.artifactVersion.toString();