Drop version field from changelog YAML (#76985)

The changelog generation process currently relies on version
information being present in the changelog YAML descriptors. However,
this makes them difficult to update in some scenarios. For example,
if a PR is merged and subsequently labelled for backporting, our
automation won't update the versions in the changelog YAML.

We can make the process more flexible by removing version data from
the changelog YAML files, and instead inferring the versions from
each changelog YAML file's existence in the git tree at each tag
in the minor series.

This change makes the process more ergonomic for developers, but
harder to test, since I can't simply concoct YAML data for a range
of versions. Instead, I've added a number of unit tests, and tried
to exercise all the relevant parts.

It is now an error to include `versions` the YAML file.

Author: pugnascotia

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/release/BreakingChangesGenerator.java

@@ -12,12 +12,12 @@
 
 import com.google.common.annotations.VisibleForTesting;
 
-import org.elasticsearch.gradle.Version;
 import org.elasticsearch.gradle.VersionProperties;
 
 import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;
+import java.io.Writer;
 import java.nio.file.Files;
 import java.util.HashMap;
 import java.util.List;
@@ -26,40 +26,50 @@
 import java.util.TreeMap;
 import java.util.stream.Collectors;
 
+import static java.util.Comparator.comparing;
+import static java.util.stream.Collectors.groupingBy;
+
 /**
  * Generates the page that lists the breaking changes and deprecations for a minor version release.
  */
 public class BreakingChangesGenerator {
 
     static void update(File templateFile, File outputFile, List<ChangelogEntry> entries) throws IOException {
         try (FileWriter output = new FileWriter(outputFile)) {
-            generateFile(Files.readString(templateFile.toPath()), output, entries);
+            generateFile(
+                QualifiedVersion.of(VersionProperties.getElasticsearch()),
+                Files.readString(templateFile.toPath()),
+                output,
+                entries
+            );
         }
     }
 
     @VisibleForTesting
-    private static void generateFile(String template, FileWriter outputWriter, List<ChangelogEntry> entries) throws IOException {
-        final Version version = VersionProperties.getElasticsearchVersion();
+    static void generateFile(QualifiedVersion version, String template, Writer outputWriter, List<ChangelogEntry> entries)
+        throws IOException {
 
         final Map<Boolean, Map<String, List<ChangelogEntry.Breaking>>> breakingChangesByNotabilityByArea = entries.stream()
             .map(ChangelogEntry::getBreaking)
             .filter(Objects::nonNull)
+            .sorted(comparing(ChangelogEntry.Breaking::getTitle))
             .collect(
-                Collectors.groupingBy(
+                groupingBy(
                     ChangelogEntry.Breaking::isNotable,
-                    Collectors.groupingBy(ChangelogEntry.Breaking::getArea, TreeMap::new, Collectors.toList())
+                    groupingBy(ChangelogEntry.Breaking::getArea, TreeMap::new, Collectors.toList())
                 )
             );
 
         final Map<String, List<ChangelogEntry.Deprecation>> deprecationsByArea = entries.stream()
             .map(ChangelogEntry::getDeprecation)
             .filter(Objects::nonNull)
-            .collect(Collectors.groupingBy(ChangelogEntry.Deprecation::getArea, TreeMap::new, Collectors.toList()));
+            .sorted(comparing(ChangelogEntry.Deprecation::getTitle))
+            .collect(groupingBy(ChangelogEntry.Deprecation::getArea, TreeMap::new, Collectors.toList()));
 
         final Map<String, Object> bindings = new HashMap<>();
         bindings.put("breakingChangesByNotabilityByArea", breakingChangesByNotabilityByArea);
         bindings.put("deprecationsByArea", deprecationsByArea);
-        bindings.put("isElasticsearchSnapshot", VersionProperties.isElasticsearchSnapshot());
+        bindings.put("isElasticsearchSnapshot", version.isSnapshot());
         bindings.put("majorDotMinor", version.getMajor() + "." + version.getMinor());
         bindings.put("majorMinor", String.valueOf(version.getMajor()) + version.getMinor());
         bindings.put("nextMajor", (version.getMajor() + 1) + ".0");

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/release/ChangelogEntry.java

@@ -37,7 +37,6 @@ public class ChangelogEntry {
     private Highlight highlight;
     private Breaking breaking;
     private Deprecation deprecation;
-    private List<String> versions;
 
     private static final ObjectMapper yamlMapper = new ObjectMapper(new YAMLFactory());
 
@@ -113,14 +112,6 @@ public void setDeprecation(Deprecation deprecation) {
         this.deprecation = deprecation;
     }
 
-    public List<String> getVersions() {
-        return versions;
-    }
-
-    public void setVersions(List<String> versions) {
-        this.versions = versions;
-    }
-
     @Override
     public boolean equals(Object o) {
         if (this == o) {
@@ -136,29 +127,27 @@ public boolean equals(Object o) {
             && Objects.equals(type, that.type)
             && Objects.equals(summary, that.summary)
             && Objects.equals(highlight, that.highlight)
-            && Objects.equals(breaking, that.breaking)
-            && Objects.equals(versions, that.versions);
+            && Objects.equals(breaking, that.breaking);
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(pr, issues, area, type, summary, highlight, breaking, versions);
+        return Objects.hash(pr, issues, area, type, summary, highlight, breaking);
     }
 
     @Override
     public String toString() {
         return String.format(
             Locale.ROOT,
-            "ChangelogEntry{pr=%d, issues=%s, area='%s', type='%s', summary='%s', highlight=%s, breaking=%s, deprecation=%s versions=%s}",
+            "ChangelogEntry{pr=%d, issues=%s, area='%s', type='%s', summary='%s', highlight=%s, breaking=%s, deprecation=%s}",
             pr,
             issues,
             area,
             type,
             summary,
             highlight,
             breaking,
-            deprecation,
-            versions
+            deprecation
         );
     }