Fix transport serialization of EnrichStatsAction.Request (#121735)

In #121256, we changed the superclass of the request to
`LocalClusterStateRequest` to make the action run on the local node
instead of the master node. Most of the actions that have been updated
thusfar to run on the local node used to extend `MasterNodeReadRequest`
and thus serialized a `local` field. This request class, however,
extended `MasterNodeRequest`, meaning that it didn't serialize that
field.

Author: nielsbauman

muted-tests.yml

@@ -382,9 +382,6 @@ tests:
 - class: org.elasticsearch.xpack.esql.action.CrossClustersCancellationIT
   method: testCancelSkipUnavailable
   issue: https://github.com/elastic/elasticsearch/issues/121631
-- class: org.elasticsearch.upgrades.UpgradeClusterClientYamlTestSuiteIT
-  method: test {p0=mixed_cluster/110_enrich/Enrich stats query smoke test for mixed cluster}
-  issue: https://github.com/elastic/elasticsearch/issues/121642
 - class: org.elasticsearch.search.CrossClusterSearchUnavailableClusterIT
   method: testSearchSkipUnavailable
   issue: https://github.com/elastic/elasticsearch/issues/121497

server/src/main/java/org/elasticsearch/action/support/local/LocalClusterStateRequest.java

@@ -41,12 +41,23 @@ protected LocalClusterStateRequest(TimeValue masterTimeout) {
      */
     @UpdateForV10(owner = UpdateForV10.Owner.DISTRIBUTED_COORDINATION)
     protected LocalClusterStateRequest(StreamInput in) throws IOException {
+        this(in, true);
+    }
+
+    /**
+     * This constructor exists solely for BwC purposes. It should exclusively be used by requests that used to extend
+     * {@link org.elasticsearch.action.support.master.MasterNodeRequest} and still need to be able to serialize incoming request.
+     */
+    @UpdateForV10(owner = UpdateForV10.Owner.DISTRIBUTED_COORDINATION)
+    protected LocalClusterStateRequest(StreamInput in, boolean readLocal) throws IOException {
         super(in);
         masterTimeout = in.readTimeValue();
         if (in.getTransportVersion().onOrAfter(TransportVersions.V_8_15_0)) {
             in.readVLong();
         }
-        in.readBoolean();
+        if (readLocal) {
+            in.readBoolean();
+        }
     }
 
     @Override

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/enrich/action/EnrichStatsAction.java

@@ -46,12 +46,13 @@ public Request(TimeValue masterNodeTimeout) {
         }
 
         /**
-         * NB prior to 9.0 this was a TransportMasterNodeReadAction so for BwC we must remain able to read these requests until
+         * NB prior to 9.0 this was a TransportMasterNodeAction so for BwC we must remain able to read these requests until
          * we no longer need to support calling this action remotely.
          */
         @UpdateForV10(owner = UpdateForV10.Owner.DATA_MANAGEMENT)
         public Request(StreamInput in) throws IOException {
-            super(in);
+            // This request extended MasterNodeRequest instead of MasterNodeReadRequest, meaning that it didn't serialize the `local` field.
+            super(in, false);
         }
 
         @Override
@@ -90,7 +91,7 @@ public List<CacheStats> getCacheStats() {
         }
 
         /**
-         * NB prior to 9.0 this was a TransportMasterNodeReadAction so for BwC we must remain able to write these responses until
+         * NB prior to 9.0 this was a TransportMasterNodeAction so for BwC we must remain able to write these responses until
          * we no longer need to support calling this action remotely.
          */
         @UpdateForV10(owner = UpdateForV10.Owner.DATA_MANAGEMENT)
@@ -181,7 +182,7 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
         public record ExecutingPolicy(String name, TaskInfo taskInfo) implements Writeable, ToXContentFragment {
 
             /**
-             * NB prior to 9.0 this was a TransportMasterNodeReadAction so for BwC we must remain able to write these responses until
+             * NB prior to 9.0 this was a TransportMasterNodeAction so for BwC we must remain able to write these responses until
              * we no longer need to support calling this action remotely.
              */
             @UpdateForV10(owner = UpdateForV10.Owner.DATA_MANAGEMENT)

x-pack/plugin/enrich/src/main/java/org/elasticsearch/xpack/enrich/action/TransportEnrichStatsAction.java

@@ -37,7 +37,7 @@ public class TransportEnrichStatsAction extends TransportLocalClusterStateAction
     private final Client client;
 
     /**
-     * NB prior to 9.0 this was a TransportMasterNodeReadAction so for BwC it must be registered with the TransportService until
+     * NB prior to 9.0 this was a TransportMasterNodeAction so for BwC it must be registered with the TransportService until
      * we no longer need to support calling this action remotely.
      */
     @UpdateForV10(owner = UpdateForV10.Owner.DATA_MANAGEMENT)