Fixing NPE when requesting [_none_] for stored_fields (#104711)

docs/changelog/104711.yaml

@@ -0,0 +1,5 @@
+pr: 104711
+summary: "Fixing NPE when requesting [_none_] for `stored_fields`"
+area: Search
+type: bug
+issues: []

server/src/main/java/org/elasticsearch/search/builder/SearchSourceBuilder.java

@@ -1337,7 +1337,10 @@ public final class SearchSourceBuilder implements Writeable, ToXContentObject, R
                         SearchSourceBuilder.STORED_FIELDS_FIELD.getPreferredName(),
                         parser
                     );
-                    searchUsage.trackSectionUsage(STORED_FIELDS_FIELD.getPreferredName());
+                    if (storedFieldsContext.fetchFields() == false
+                        || (storedFieldsContext.fieldNames() != null && storedFieldsContext.fieldNames().size() > 0)) {
+                        searchUsage.trackSectionUsage(STORED_FIELDS_FIELD.getPreferredName());
+                    }
                 } else if (SORT_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                     sort(parser.text());
                 } else if (PROFILE_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
@@ -1493,7 +1496,8 @@ public final class SearchSourceBuilder implements Writeable, ToXContentObject, R
             } else if (token == XContentParser.Token.START_ARRAY) {
                 if (STORED_FIELDS_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                     storedFieldsContext = StoredFieldsContext.fromXContent(STORED_FIELDS_FIELD.getPreferredName(), parser);
-                    if (storedFieldsContext.fieldNames().size() > 0 || storedFieldsContext.fetchFields() == false) {
+                    if (storedFieldsContext.fetchFields() == false
+                        || (storedFieldsContext.fieldNames() != null && storedFieldsContext.fieldNames().size() > 0)) {
                         searchUsage.trackSectionUsage(STORED_FIELDS_FIELD.getPreferredName());
                     }
                 } else if (DOCVALUE_FIELDS_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {

server/src/test/java/org/elasticsearch/search/builder/SearchSourceBuilderTests.java

@@ -65,6 +65,7 @@ import java.io.IOException;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Supplier;
 import java.util.function.ToLongFunction;
@@ -592,6 +593,28 @@ public class SearchSourceBuilderTests extends AbstractSearchTestCase {
         }
     }
 
+    public void testStoredFieldsUsage() throws IOException {
+        Set<String> storedFieldRestVariations = Set.of(
+            "{\"stored_fields\" : [\"_none_\"]}",
+            "{\"stored_fields\" : \"_none_\"}",
+            "{\"stored_fields\" : [\"field\"]}",
+            "{\"stored_fields\" : \"field\"}"
+        );
+        for (String storedFieldRest : storedFieldRestVariations) {
+            SearchUsageHolder searchUsageHolder = new UsageService().getSearchUsageHolder();
+            try (XContentParser parser = createParser(JsonXContent.jsonXContent, storedFieldRest)) {
+                new SearchSourceBuilder().parseXContent(parser, true, searchUsageHolder);
+                SearchUsageStats searchUsageStats = searchUsageHolder.getSearchUsageStats();
+                Map<String, Long> sectionsUsage = searchUsageStats.getSectionsUsage();
+                assertEquals(
+                    "Failed to correctly parse and record usage of '" + storedFieldRest + "'",
+                    1L,
+                    sectionsUsage.get("stored_fields").longValue()
+                );
+            }
+        }
+    }
+
     public void testEmptySectionsAreNotTracked() throws IOException {
         SearchUsageHolder searchUsageHolder = new UsageService().getSearchUsageHolder();