Fixed the failing tests

Author: mridula-s109

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

@@ -359,8 +359,6 @@ protected RetrieverBuilder doRewrite(QueryRewriteContext ctx) {
             if (fieldsInnerRetrievers.isEmpty() == false) {
                 // TODO: This is a incomplete solution as it does not address other incomplete copy issues
                 // (such as dropping the retriever name and min score)
-                // Top-level weights are intentionally reset to defaults here because per-field weighting
-                // is handled in the nested structures (MMQ/inference RRF) created by generateInnerRetrievers
                 float[] weights = createDefaultWeights(fieldsInnerRetrievers);
                 rewritten = new RRFRetrieverBuilder(fieldsInnerRetrievers, null, null, rankWindowSize, rankConstant, weights);
                 rewritten.getPreFilterQueryBuilders().addAll(preFilterQueryBuilders);
@@ -369,7 +367,6 @@ protected RetrieverBuilder doRewrite(QueryRewriteContext ctx) {
                 rewritten = new StandardRetrieverBuilder(new MatchNoneQueryBuilder());
             }
         }
-
         return rewritten;
     }
 

x-pack/plugin/rank-rrf/src/yamlRestTest/resources/rest-api-spec/test/rrf/310_rrf_retriever_simplified.yml

@@ -184,11 +184,11 @@ setup:
               fields: [ "dense_inference", "sparse_inference" ]
               query: "distributed, RESTful, search engine"
 
-  # Semantic-only match, so max score is 1
+  # Semantic-only match, so max RRF score for rank 1 with default rank_constant (60) is 1/(60+1) = 0.01639
   - match: { hits.total.value: 3 }
   - length: { hits.hits: 3 }
   - match: { hits.hits.0._id: "2" }
-  - close_to: { hits.hits.0._score: { value: 1.0, error: 0.0001 } }
+  - close_to: { hits.hits.0._score: { value: 0.01639, error: 0.0001 } }
   - match: { hits.hits.1._id: "3" }
   - lt: { hits.hits.1._score: 1.0 }
   - match: { hits.hits.2._id: "1" }
@@ -205,11 +205,11 @@ setup:
               fields: [ "dense_inference^3", "sparse_inference" ]
               query: "distributed, RESTful, search engine"
 
-  # Semantic-only match, so max score is 1
+  # Semantic-only match with boosted dense_inference field, so max RRF score for rank 1 is still 1/(60+1) = 0.01639
   - match: { hits.total.value: 3 }
   - length: { hits.hits: 3 }
   - match: { hits.hits.0._id: "3" }
-  - close_to: { hits.hits.0._score: { value: 1.0, error: 0.0001 } }
+  - close_to: { hits.hits.0._score: { value: 0.01639, error: 0.0001 } }
   - match: { hits.hits.1._id: "2" }
   - lt: { hits.hits.1._score: 1.0 }
   - match: { hits.hits.2._id: "1" }