code: @CallSuper
      @Override
      protected void onSave(Bundle state) {
          for (int i = requested.size() - 1; i >= 0; i--) {
              int restartableId = requested.get(i);
              Subscription subscription = restartableSubscriptions.get(restartableId);
              if (subscription != null && subscription.isUnsubscribed())
                  requested.remove(i);
          }
          state.putIntegerArrayList(REQUESTED_KEY, requested);
      }
docs: {@inheritDoc}