Update driver-sync/src/test/functional/com/mongodb/client/WithTransactionProseTest.java

Co-authored-by: Valentin Kovalenko <valentin.male.kovalenko@gmail.com>

Author: nhachicha

driver-sync/src/test/functional/com/mongodb/client/WithTransactionProseTest.java

@@ -271,10 +271,7 @@ void testRetryBackoffIsEnforced() {
         long withBackoffTime;
         try (ClientSession session = client.startSession()) {
             long startNanos = System.nanoTime();
-            session.withTransaction(() -> {
-                collection.insertOne(session, Document.parse("{ _id : 'backoff-test-full-jitter' }"));
-                return null;
-            });
+            session.withTransaction(() -> collection.insertOne(session, Document.parse("{ _id : 'backoff-test-full-jitter' }")));
             withBackoffTime = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startNanos);
         } finally {
             ExponentialBackoff.clearTestJitterSupplier();