Link to release notes from upgrade issues

Closes gh-31544

buildSrc/src/main/java/org/springframework/boot/build/bom/Library.java

@@ -146,8 +146,12 @@ public class Library {
 	}
 
 	public Map<String, String> getLinks() {
+		return getLinks(this.version);
+	}
+
+	public Map<String, String> getLinks(LibraryVersion version) {
 		Map<String, String> links = new TreeMap<>();
-		this.links.forEach((name, linkFactory) -> links.put(name, linkFactory.apply(this.version)));
+		this.links.forEach((name, linkFactory) -> links.put(name, linkFactory.apply(version)));
 		return Collections.unmodifiableMap(links);
 	}
 

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

@@ -17,6 +17,7 @@
 package org.springframework.boot.build.bom.bomr;
 
 import java.time.OffsetDateTime;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.function.BiPredicate;
@@ -32,6 +33,7 @@ import org.slf4j.LoggerFactory;
 import org.springframework.boot.build.bom.BomExtension;
 import org.springframework.boot.build.bom.Library;
 import org.springframework.boot.build.bom.bomr.ReleaseSchedule.Release;
+import org.springframework.boot.build.bom.bomr.github.Issue;
 import org.springframework.boot.build.bom.bomr.github.Milestone;
 import org.springframework.boot.build.bom.bomr.version.DependencyVersion;
 import org.springframework.boot.build.properties.BuildProperties;
@@ -67,20 +69,33 @@ public abstract class MoveToSnapshots extends UpgradeDependencies {
 
 	@Override
 	protected String issueTitle(Upgrade upgrade) {
+		return "Upgrade to " + description(upgrade);
+	}
+
+	private String description(Upgrade upgrade) {
 		String snapshotVersion = upgrade.getVersion().toString();
 		String releaseVersion = snapshotVersion.substring(0, snapshotVersion.length() - "-SNAPSHOT".length());
-		return "Upgrade to " + upgrade.getLibrary().getName() + " " + releaseVersion;
+		return upgrade.getLibrary().getName() + " " + releaseVersion;
+	}
+
+	@Override
+	protected String issueBody(Upgrade upgrade, Issue existingUpgrade) {
+		String releaseNotes = upgrade.getLibrary().getLinks().get("releaseNotes");
+		List<String> lines = new ArrayList<>();
+		String description = description(upgrade);
+		if (releaseNotes != null) {
+			lines.add("Upgrade to [%s](%s).".formatted(description, releaseNotes));
+		}
+		lines.add("Upgrade to %s.".formatted(description));
+		if (existingUpgrade != null) {
+			lines.add("Supersedes #" + existingUpgrade.getNumber());
+		}
+		return String.join("\\r\\n\\r\\n", lines);
 	}
 
 	@Override
 	protected String commitMessage(Upgrade upgrade, int issueNumber) {
-		return "Start building against " + upgrade.getLibrary().getName() + " " + releaseVersion(upgrade) + " snapshots"
+		return "Start building against " + description(upgrade) + " snapshots" + "\n\nSee gh-" + issueNumber;
-				+ "\n\nSee gh-" + issueNumber;
-	}
-
-	private String releaseVersion(Upgrade upgrade) {
-		String snapshotVersion = upgrade.getVersion().toString();
-		return snapshotVersion.substring(0, snapshotVersion.length() - "-SNAPSHOT".length());
 	}
 
 	@Override

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

@@ -16,6 +16,9 @@
 
 package org.springframework.boot.build.bom.bomr;
 
+import java.util.ArrayList;
+import java.util.List;
+
 import javax.inject.Inject;
 
 import org.gradle.api.Task;
@@ -24,6 +27,8 @@ import org.gradle.api.artifacts.dsl.RepositoryHandler;
 import org.gradle.api.artifacts.repositories.MavenArtifactRepository;
 
 import org.springframework.boot.build.bom.BomExtension;
+import org.springframework.boot.build.bom.Library.LibraryVersion;
+import org.springframework.boot.build.bom.bomr.github.Issue;
 import org.springframework.boot.build.properties.BuildProperties;
 
 /**
@@ -68,4 +73,23 @@ public abstract class UpgradeBom extends UpgradeDependencies {
 		return issueTitle(upgrade) + "\n\nCloses gh-" + issueNumber;
 	}
 
+	@Override
+	protected String issueBody(Upgrade upgrade, Issue existingUpgrade) {
+		String releaseNotes = upgrade.getLibrary()
+			.getLinks(new LibraryVersion(upgrade.getVersion()))
+			.get("releaseNotes");
+		List<String> lines = new ArrayList<>();
+		String description = upgrade.getLibrary().getName() + " " + upgrade.getVersion();
+		if (releaseNotes != null) {
+			lines.add("Upgrade to [%s](%s).".formatted(description, releaseNotes));
+		}
+		else {
+			lines.add("Upgrade to %s.".formatted(description));
+		}
+		if (existingUpgrade != null) {
+			lines.add("Supersedes #" + existingUpgrade.getNumber());
+		}
+		return String.join("\\r\\n\\r\\n", lines);
+	}
+
 }

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

@@ -119,11 +119,12 @@ public abstract class UpgradeDependencies extends DefaultTask {
 		System.out.println("");
 		for (Upgrade upgrade : upgrades) {
 			System.out.println(upgrade.getLibrary().getName() + " " + upgrade.getVersion());
-			String title = issueTitle(upgrade);
 			Issue existingUpgradeIssue = findExistingUpgradeIssue(existingUpgradeIssues, upgrade);
 			try {
 				Path modified = this.upgradeApplicator.apply(upgrade);
-				int issueNumber = getOrOpenUpgradeIssue(repository, issueLabels, milestone, title,
+				String title = issueTitle(upgrade);
+				String body = issueBody(upgrade, existingUpgradeIssue);
+				int issueNumber = getOrOpenUpgradeIssue(repository, issueLabels, milestone, title, body,
 						existingUpgradeIssue);
 				if (existingUpgradeIssue != null && existingUpgradeIssue.getState() == Issue.State.CLOSED) {
 					existingUpgradeIssue.label(Arrays.asList("type: task", "status: superseded"));
@@ -151,11 +152,10 @@ public abstract class UpgradeDependencies extends DefaultTask {
 	}
 
 	private int getOrOpenUpgradeIssue(GitHubRepository repository, List<String> issueLabels, Milestone milestone,
-			String title, Issue existingUpgradeIssue) {
+			String title, String body, Issue existingUpgradeIssue) {
 		if (existingUpgradeIssue != null && existingUpgradeIssue.getState() == Issue.State.OPEN) {
 			return existingUpgradeIssue.getNumber();
 		}
-		String body = (existingUpgradeIssue != null) ? "Supersedes #" + existingUpgradeIssue.getNumber() : "";
 		return repository.openIssue(title, body, issueLabels, milestone);
 	}
 
@@ -289,4 +289,6 @@ public abstract class UpgradeDependencies extends DefaultTask {
 
 	protected abstract String commitMessage(Upgrade upgrade, int issueNumber);
 
+	protected abstract String issueBody(Upgrade upgrade, Issue existingUpgrade);
+
 }