Entity id passed as slug, not loaded as entity in routematch Drupal 8

routing.yml

#When a slug passed in route doesn't load entity on getParameter, you need to pass the entity type as options
#in routing.yml so that the entityconverter knows what it is.

#@link https://www.drupal.org/docs/8/api/routing-system/how-a-node-id-gets-converted-to-its-actual-node-object
#in your routing.yml

route_name:
  path: /path/{foo}
  options:
    parameters:
      foo:
        type: entity:foo_entity