[BUG] Agent framework: Fix SearchIndexTool to parse special floating point values and NaN (opensearch-project#3754)

* fix: support null/NaN values returned from document search

Signed-off-by: Pavan Yekbote <[email protected]>

* spotless

Signed-off-by: Pavan Yekbote <[email protected]>

* chore: add document for NaN test case

Signed-off-by: Pavan Yekbote <[email protected]>

* fix: use static variable for gson instance

Signed-off-by: Pavan Yekbote <[email protected]>

---------

Signed-off-by: Pavan Yekbote <[email protected]>
Signed-off-by: Abdul Muneer Kolarkunnu <[email protected]>

Author: pyek-bot

ml-algorithms/src/main/java/org/opensearch/ml/engine/tools/SearchIndexTool.java

@@ -27,11 +27,12 @@
 import org.opensearch.ml.common.transport.connector.MLConnectorSearchAction;
 import org.opensearch.ml.common.transport.model.MLModelSearchAction;
 import org.opensearch.ml.common.transport.model_group.MLModelGroupSearchAction;
-import org.opensearch.ml.common.utils.StringUtils;
 import org.opensearch.search.SearchHit;
 import org.opensearch.search.builder.SearchSourceBuilder;
 import org.opensearch.transport.client.Client;
 
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 
@@ -62,6 +63,8 @@ public class SearchIndexTool implements Tool {
         + "Invalid value: \\n{\\\"match\\\":{\\\"population_description\\\":\\\"seattle 2023 population\\\"}}\\nThe value is invalid because the match not wrapped by \\\"query\\\".\","
         + "\"additionalProperties\":false}},\"required\":[\"index\",\"query\"],\"additionalProperties\":false}";
 
+    private static final Gson GSON = new GsonBuilder().serializeSpecialFloatingPointValues().create();
+
     private String name = TYPE;
     private Map<String, Object> attributes;
     private String description = DEFAULT_DESCRIPTION;
@@ -114,7 +117,7 @@ private static Map<String, Object> processResponse(SearchHit hit) {
     public <T> void run(Map<String, String> parameters, ActionListener<T> listener) {
         try {
             String input = parameters.get(INPUT_FIELD);
-            JsonObject jsonObject = StringUtils.gson.fromJson(input, JsonObject.class);
+            JsonObject jsonObject = GSON.fromJson(input, JsonObject.class);
             String index = Optional.ofNullable(jsonObject).map(x -> x.get(INDEX_FIELD)).map(JsonElement::getAsString).orElse(null);
             String query = Optional.ofNullable(jsonObject).map(x -> x.get(QUERY_FIELD)).map(JsonElement::toString).orElse(null);
             if (index == null || query == null) {
@@ -131,7 +134,7 @@ public <T> void run(Map<String, String> parameters, ActionListener<T> listener)
                     for (SearchHit hit : hits) {
                         String doc = AccessController.doPrivileged((PrivilegedExceptionAction<String>) () -> {
                             Map<String, Object> docContent = processResponse(hit);
-                            return StringUtils.gson.toJson(docContent);
+                            return GSON.toJson(docContent);
                         });
                         contextBuilder.append(doc).append("\n");
                     }

ml-algorithms/src/test/resources/org/opensearch/ml/engine/tools/retrieval_tool_search_response.json

@@ -29,6 +29,14 @@
         "_source": {
           "passage_text": "the price of the api is 2$ per invocation"
         }
+      },
+      {
+        "_index": "hybrid-index",
+        "_id": "3",
+        "_score": 0.9,
+        "_source": {
+          "passage_text": null
+        }
       }
     ]
   }