Java/ninja revert transactional change so data persists (#3217)

* Java/ninja revert transactional change so data persists

* Use transactional to persist but only once per update

* Update HelloDbController.java

frameworks/Java/ninja-standalone/src/main/java/controllers/HelloDbController.java

@@ -10,6 +10,7 @@
 
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
+import com.google.inject.persist.Transactional;
 import ninja.jpa.UnitOfWork;
 import ninja.params.Param;
 
@@ -62,12 +63,17 @@ public Result update(@Param("queries") Integer queries) {
         // now update stuff:
         for (World world : worlds) {
             world.randomNumber = ThreadLocalRandom.current().nextInt(DB_ROWS) + 1;
-            worldDao.put(world);
+            this.updateWorld(world);
         }
 
         return Results.json().render(worlds);
     }
 
+    @Transactional
+    public void updateWorld(World world) {
+        worldDao.put(world);
+    }
+
     private World getRandomWorld() {
         return worldDao.get(ThreadLocalRandom.current().nextInt(DB_ROWS) + 1);
     }