commerce-8.x-2.8/modules/checkout/commerce_checkout.services.yml

services:
  commerce_checkout.chain_checkout_flow_resolver:
    class: Drupal\commerce_checkout\Resolver\ChainCheckoutFlowResolver
    tags:
      - { name: service_collector, call: addResolver, tag: commerce_checkout.checkout_flow_resolver }

  commerce_checkout.default_checkout_flow_resolver:
    class: Drupal\commerce_checkout\Resolver\DefaultCheckoutFlowResolver
    arguments: ['@entity_type.manager']
    tags:
      - { name: commerce_checkout.checkout_flow_resolver, priority: -100 }

  commerce_checkout.checkout_order_manager:
    class: Drupal\commerce_checkout\CheckoutOrderManager
    arguments: ['@commerce_checkout.chain_checkout_flow_resolver']

  plugin.manager.commerce_checkout_flow:
    class: Drupal\commerce_checkout\CheckoutFlowManager
    parent: default_plugin_manager

  plugin.manager.commerce_checkout_pane:
    class: Drupal\commerce_checkout\CheckoutPaneManager
    parent: default_plugin_manager