code: @RequestMapping(path = "/{customerId}", method=RequestMethod.GET)
      public ResponseEntity<Customer> getCustomer(@PathVariable("customerId") Long customerId, @RequestParam(required=true) String name){
          Customer customer = customerService.getCustomer(customerId);
          if(customer != null){
              return new ResponseEntity<Customer>(customer, HttpStatus.OK);
          }
          return new ResponseEntity<Customer>(HttpStatus.NOT_FOUND);
      }
docs: Get a specific customer by id
  @param customerId id of the customer
  @response 200
  @response 404 if customer doesn't exists
  @return the customer or null