code: private void handleLoadFromUserDataService(final User loadedUser,
                                                 final Callback<List<Recommendation>> recommendationsCallback) {
  
          /** Add a runnable to the callbacks list. */
          callbacks.add(() -> {
              List<Recommendation> recommendations = runRulesEngineAgainstUser(loadedUser);
              recommendationsCallback.accept(recommendations);
          });
  
  //        callbacks.add(new Runnable() {
  //            @Override
  //            public void run() {
  //                List<Recommendation> recommendations = runRulesEngineAgainstUser(loadedUser);
  //                recommendationsCallback.accept(recommendations);
  //            }
  //        });
      }
docs: Handle defered recommendations based on user loads.