HOTFIX: close iterator to avoid resource leak (#14624)

Reviewers: Hao Li <hli@confluent.io>, Bill Bejeck <bill@confluent.io>

streams/src/main/java/org/apache/kafka/streams/kstream/internals/KStreamSessionWindowAggregate.java

@@ -264,12 +264,13 @@ public class KStreamSessionWindowAggregate<KIn, VIn, VAgg> implements KStreamAgg
                                   final long emitRangeUpperBound) {
             final long startMs = time.milliseconds();
 
+            int emittedCount = 0;
+
             // Only time ordered (indexed) session store should have implemented
             // this function, otherwise a not-supported exception would throw
-            final KeyValueIterator<Windowed<KIn>, VAgg> windowToEmit = store
-                .findSessions(emitRangeLowerBound, emitRangeUpperBound);
+            try (final KeyValueIterator<Windowed<KIn>, VAgg> windowToEmit = store
+                    .findSessions(emitRangeLowerBound, emitRangeUpperBound)) {
 
-            int emittedCount = 0;
                 while (windowToEmit.hasNext()) {
                     emittedCount++;
                     final KeyValue<Windowed<KIn>, VAgg> kv = windowToEmit.next();
@@ -281,6 +282,7 @@ public class KStreamSessionWindowAggregate<KIn, VIn, VAgg> implements KStreamAgg
                             .withTimestamp(kv.key.window().end())
                             .withHeaders(record.headers()));
                 }
+            }
             emittedRecordsSensor.record(emittedCount);
             emitFinalLatencySensor.record(time.milliseconds() - startMs);