/**
  * @param Request $request
  * @param Product $product
  * @return \Illuminate\Http\RedirectResponse
  */
 public function update(Request $request, Product $product)
 {
     // if a plan is selected authorize first
     if ($planId = $request->input('plan')) {
         $plan = $this->shippingPlanRepository->find($planId);
         $this->authorize('update', $plan);
         $product->shippingPlans()->sync([$planId]);
     } else {
         $product->shippingPlans()->sync([]);
     }
     return $this->success('edit');
 }