Fix(rerank): Correct relevanceScore setter to use double to avoid format

exception
- Changed setRelevanceScore parameter from int to double
- Prevented IllegalFormatConversionException when formatting with %.4f

Signed-off-by: nirsa <[email protected]>

Author: KoreaNirsa

spring-ai-rag/src/main/java/org/springframework/ai/rag/postretrieval/rerank/CohereReranker.java

@@ -2,6 +2,7 @@
 
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -81,7 +82,12 @@ public List<Document> rerank(String query, List<Document> documents, int topN) {
         return sendRerankRequest(payload)
                 .map(results -> results.stream()
                     .sorted(Comparator.comparingDouble(RerankResponse.Result::getRelevanceScore).reversed())
-                    .map(r -> documents.get(r.getIndex()))
+                    .map(r -> {
+                        Document original = documents.get(r.getIndex());
+                        Map<String, Object> metadata = new HashMap<>(original.getMetadata());
+                        metadata.put("score", String.format("%.4f", r.getRelevanceScore()));
+                        return new Document(original.getText(), metadata);
+                    })
                     .toList())
                 .orElseGet(() -> {
                     logger.warn("Cohere response is null or invalid");

spring-ai-rag/src/main/java/org/springframework/ai/rag/postretrieval/rerank/RerankResponse.java

@@ -30,7 +30,7 @@ public static class Result {
         private int index;
 
         @JsonProperty("relevance_score")
-        private int relevanceScore;
+        private double relevanceScore;
 
         public int getIndex() {
             return index;
@@ -40,11 +40,11 @@ public void setIndex(int index) {
             this.index = index;
         }
 
-        public int getRelevanceScore() {
+        public double getRelevanceScore() {
             return relevanceScore;
         }
 
-        public void setRelevanceScore(int relevanceScore) {
+        public void setRelevanceScore(double relevanceScore) {
             this.relevanceScore = relevanceScore;
         }
     }