arch-8.x-1.x-dev/modules/payment/modules/cod/arch_payment_cod.routing.yml

arch_payment_cod.success:
  path: '/payment/cod/success'
  defaults:
    _controller: '\Drupal\arch_payment_cod\Controller\CodPaymentController::paymentSuccess'
    _title: 'Successful Payment'
    _title_context: 'arch_payment_cod'
  requirements:
    _permission: 'access content'