bee_hotel-1.x-dev/modules/beehotel_addtocart/beehotel_addtocart.routing.yml

beehotel_addtocart.list:
 path: '/add/product/{productId}'
 defaults:
   _controller: '\Drupal\beehotel_addtocart\Controller\BeeHotelAddToCart::addToCart'
   _title: ''
 requirements:
   _permission: 'access content'
   productId: \d+