Handle projectRouting over the wire

Author: pawankartik-elastic

server/src/main/java/org/elasticsearch/action/search/MultiSearchRequest.java

@@ -9,6 +9,7 @@
 
 package org.elasticsearch.action.search;
 
+import org.elasticsearch.TransportVersion;
 import org.elasticsearch.action.ActionRequestValidationException;
 import org.elasticsearch.action.CompositeIndicesRequest;
 import org.elasticsearch.action.IndicesRequest;
@@ -62,6 +63,8 @@ public class MultiSearchRequest extends LegacyActionRequest implements Composite
     @Nullable
     private String projectRouting;
 
+    private static final TransportVersion MSEARCH_PROJECT_ROUTING = TransportVersion.fromName("msearch_project_routing");
+
     public MultiSearchRequest() {}
 
     /**
@@ -141,13 +144,21 @@ public MultiSearchRequest(StreamInput in) throws IOException {
             SearchRequest request = new SearchRequest(in);
             requests.add(request);
         }
+        if (in.getTransportVersion().supports(MSEARCH_PROJECT_ROUTING)) {
+            this.projectRouting = in.readOptionalString();
+        } else {
+            this.projectRouting = null;
+        }
     }
 
     @Override
     public void writeTo(StreamOutput out) throws IOException {
         super.writeTo(out);
         out.writeVInt(maxConcurrentSearchRequests);
         out.writeCollection(requests);
+        if (out.getTransportVersion().supports(MSEARCH_PROJECT_ROUTING)) {
+            out.writeOptionalString(this.projectRouting);
+        }
     }
 
     @Override

server/src/main/resources/transport/definitions/referable/msearch_project_routing.csv

@@ -0,0 +1 @@
+9234000

server/src/main/resources/transport/upper_bounds/9.3.csv

@@ -1 +1 @@
-ml_inference_nvidia_added,9233000
+msearch_project_routing,9234000