Update index deprecation checks to return minimum writable index version for use with ignore setting

Author: lukewhiting

x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/DataStreamDeprecationChecks.java

@@ -38,6 +38,7 @@ static DeprecationIssue oldIndicesCheck(DataStream dataStream, ClusterState clus
                 false,
                 ofEntries(
                     entry("reindex_required", true),
+                    entry("minimum_writable_version_after_upgrade", DeprecatedIndexPredicate.MINIMUM_WRITEABLE_VERSION_AFTER_UPGRADE.id()),
                     entry("total_backing_indices", backingIndices.size()),
                     entry("indices_requiring_upgrade_count", indicesNeedingUpgrade.size()),
                     entry("indices_requiring_upgrade", indicesNeedingUpgrade)

x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/IndexDeprecationChecks.java

@@ -20,14 +20,16 @@
 import org.elasticsearch.xpack.core.deprecation.DeprecationIssue;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
 import java.util.function.Function;
 
+import static java.util.Map.entry;
+import static java.util.Map.ofEntries;
+
 /**
  * Index-specific deprecation checks
  */
@@ -44,7 +46,10 @@ static DeprecationIssue oldIndicesCheck(IndexMetadata indexMetadata, ClusterStat
                 "https://www.elastic.co/guide/en/elasticsearch/reference/master/breaking-changes-9.0.html",
                 "This index has version: " + currentCompatibilityVersion.toReleaseVersion(),
                 false,
-                Collections.singletonMap("reindex_required", true)
+                ofEntries(
+                    entry("reindex_required", true),
+                    entry("minimum_writable_version_after_upgrade", DeprecatedIndexPredicate.MINIMUM_WRITEABLE_VERSION_AFTER_UPGRADE.id())
+                )
             );
         }
         return null;