Modified LinearRetrieverBuilder to propagate top level normalizer to each and every sub level

Author: mridula-s109

x-pack/plugin/rank-rrf/src/main/java/org/elasticsearch/xpack/rank/linear/LinearRetrieverBuilder.java

@@ -43,6 +43,7 @@
 import static org.elasticsearch.action.ValidateActions.addValidationError;
 import static org.elasticsearch.xcontent.ConstructingObjectParser.optionalConstructorArg;
 import static org.elasticsearch.xpack.rank.RankRRFFeatures.LINEAR_RETRIEVER_SUPPORTED;
+import static org.elasticsearch.xpack.rank.linear.LinearRetrieverComponent.DEFAULT_NORMALIZER;
 import static org.elasticsearch.xpack.rank.linear.LinearRetrieverComponent.DEFAULT_WEIGHT;
 
 /**
@@ -82,17 +83,17 @@ public final class LinearRetrieverBuilder extends CompoundRetrieverBuilder<Linea
             List<LinearRetrieverComponent> retrieverComponents = args[0] == null ? List.of() : (List<LinearRetrieverComponent>) args[0];
             List<String> fields = (List<String>) args[1];
             String query = (String) args[2];
-            ScoreNormalizer normalizer = args[3] == null ? null : ScoreNormalizer.valueOf((String) args[3]);
+            ScoreNormalizer normalizer = args[3] == null ? DEFAULT_NORMALIZER : ScoreNormalizer.valueOf((String) args[3]);
             int rankWindowSize = args[4] == null ? RankBuilder.DEFAULT_RANK_WINDOW_SIZE : (int) args[4];
 
             int index = 0;
             float[] weights = new float[retrieverComponents.size()];
             ScoreNormalizer[] normalizers = new ScoreNormalizer[retrieverComponents.size()];
+            Arrays.fill(normalizers, normalizer);
             List<RetrieverSource> innerRetrievers = new ArrayList<>();
             for (LinearRetrieverComponent component : retrieverComponents) {
                 innerRetrievers.add(RetrieverSource.from(component.retriever));
                 weights[index] = component.weight;
-                normalizers[index] = component.normalizer;
                 index++;
             }
             return new LinearRetrieverBuilder(innerRetrievers, fields, query, normalizer, rankWindowSize, weights, normalizers);
@@ -221,17 +222,6 @@ public ActionRequestValidationException validate(
                 ),
                 validationException
             );
-        } else if (innerRetrievers.isEmpty() == false && normalizer != null) {
-            validationException = addValidationError(
-                String.format(
-                    Locale.ROOT,
-                    "[%s] [%s] cannot be provided when [%s] is specified",
-                    getName(),
-                    NORMALIZER_FIELD.getPreferredName(),
-                    RETRIEVERS_FIELD.getPreferredName()
-                ),
-                validationException
-            );
         }
 
         return validationException;
@@ -393,7 +383,6 @@ public void doToXContent(XContentBuilder builder, Params params) throws IOExcept
                 builder.startObject();
                 builder.field(LinearRetrieverComponent.RETRIEVER_FIELD.getPreferredName(), entry.retriever());
                 builder.field(LinearRetrieverComponent.WEIGHT_FIELD.getPreferredName(), weights[index]);
-                builder.field(LinearRetrieverComponent.NORMALIZER_FIELD.getPreferredName(), normalizers[index].getName());
                 builder.endObject();
                 index++;
             }

x-pack/plugin/rank-rrf/src/main/java/org/elasticsearch/xpack/rank/linear/LinearRetrieverComponent.java

@@ -25,7 +25,7 @@ public class LinearRetrieverComponent implements ToXContentObject {
 
     public static final ParseField RETRIEVER_FIELD = new ParseField("retriever");
     public static final ParseField WEIGHT_FIELD = new ParseField("weight");
-    public static final String DEFAULT_NORMALIZER = IdentityScoreNormalizer.INSTANCE.getName();
+    public static final ScoreNormalizer DEFAULT_NORMALIZER = IdentityScoreNormalizer.INSTANCE;
 
     static final float DEFAULT_WEIGHT = 1f;