Fix transport serialization of EnrichStatsAction.Request

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)