Adjust BWC version on aliases version upon backport

This commit adjusts the BWC on the introduction of aliases version to
index metadata after that functionality was backported to the 7.x
branch, which is currently targeting 7.1.0.

server/src/main/java/org/elasticsearch/cluster/metadata/IndexMetaData.java

@@ -711,10 +711,10 @@ public class IndexMetaData implements Diffable<IndexMetaData>, ToXContentFragmen
             version = in.readLong();
             mappingVersion = in.readVLong();
             settingsVersion = in.readVLong();
-            if (in.getVersion().onOrAfter(Version.V_8_0_0)) {
+            if (in.getVersion().onOrAfter(Version.V_7_1_0)) {
                 aliasesVersion = in.readVLong();
             } else {
-                aliasesVersion = 0;
+                aliasesVersion = 1;
             }
             state = State.fromId(in.readByte());
             settings = Settings.readSettingsFromStream(in);
@@ -738,7 +738,7 @@ public class IndexMetaData implements Diffable<IndexMetaData>, ToXContentFragmen
             out.writeLong(version);
             out.writeVLong(mappingVersion);
             out.writeVLong(settingsVersion);
-            if (out.getVersion().onOrAfter(Version.V_8_0_0)) {
+            if (out.getVersion().onOrAfter(Version.V_7_1_0)) {
                 out.writeVLong(aliasesVersion);
             }
             out.writeByte(state.id);
@@ -776,7 +776,7 @@ public class IndexMetaData implements Diffable<IndexMetaData>, ToXContentFragmen
         builder.version(in.readLong());
         builder.mappingVersion(in.readVLong());
         builder.settingsVersion(in.readVLong());
-        if (in.getVersion().onOrAfter(Version.V_8_0_0)) {
+        if (in.getVersion().onOrAfter(Version.V_7_1_0)) {
             builder.aliasesVersion(in.readVLong());
         }
         builder.setRoutingNumShards(in.readInt());
@@ -818,7 +818,7 @@ public class IndexMetaData implements Diffable<IndexMetaData>, ToXContentFragmen
         out.writeLong(version);
         out.writeVLong(mappingVersion);
         out.writeVLong(settingsVersion);
-        if (out.getVersion().onOrAfter(Version.V_8_0_0)) {
+        if (out.getVersion().onOrAfter(Version.V_7_1_0)) {
             out.writeVLong(aliasesVersion);
         }
         out.writeInt(routingNumShards);
@@ -1414,8 +1414,8 @@ public class IndexMetaData implements Diffable<IndexMetaData>, ToXContentFragmen
             if (Assertions.ENABLED && Version.indexCreated(builder.settings).onOrAfter(Version.V_6_5_0)) {
                 assert settingsVersion : "settings version should be present for indices created on or after 6.5.0";
             }
-            if (Assertions.ENABLED && Version.indexCreated(builder.settings).onOrAfter(Version.V_8_0_0)) {
-                assert aliasesVersion : "aliases version should be present for indices created on or after 8.0.0";
+            if (Assertions.ENABLED && Version.indexCreated(builder.settings).onOrAfter(Version.V_7_1_0)) {
+                assert aliasesVersion : "aliases version should be present for indices created on or after 7.1.0";
             }
             return builder.build();
         }

server/src/test/java/org/elasticsearch/cluster/metadata/MetaDataIndexAliasesServiceTests.java

@@ -102,14 +102,14 @@ public class MetaDataIndexAliasesServiceTests extends ESTestCase {
     public void testMultipleIndices() {
         final var length = randomIntBetween(2, 8);
         final var indices = new HashSet<String>(length);
-        var before = ClusterState.builder(ClusterName.DEFAULT).build();
+        ClusterState before = ClusterState.builder(ClusterName.DEFAULT).build();
         final var addActions = new ArrayList<AliasAction>(length);
         for (int i = 0; i < length; i++) {
             final String index = randomValueOtherThanMany(v -> indices.add(v) == false, () -> randomAlphaOfLength(8));
             before = createIndex(before, index);
             addActions.add(new AliasAction.Add(index, "alias-" + index, null, null, null, null));
         }
-        final var afterAddingAliasesToAll = service.innerExecute(before, addActions);
+        final ClusterState afterAddingAliasesToAll = service.innerExecute(before, addActions);
         assertAliasesVersionIncreased(indices.toArray(new String[0]), before, afterAddingAliasesToAll);
 
         // now add some aliases randomly
@@ -121,7 +121,7 @@ public class MetaDataIndexAliasesServiceTests extends ESTestCase {
                 randomIndices.add(index);
             }
         }
-        final var afterAddingRandomAliases = service.innerExecute(afterAddingAliasesToAll, randomAddActions);
+        final ClusterState afterAddingRandomAliases = service.innerExecute(afterAddingAliasesToAll, randomAddActions);
         assertAliasesVersionIncreased(randomIndices.toArray(new String[0]), afterAddingAliasesToAll, afterAddingRandomAliases);
         assertAliasesVersionUnchanged(
                 Sets.difference(indices, randomIndices).toArray(new String[0]),