farm-2.x-dev/modules/core/kml/farm_kml.services.yml

services:
  serializer.farm_kml.kml.encoder:
    class: Drupal\farm_kml\Encoder\Kml
    tags:
      - { name: encoder, priority: 10, format: geometry_kml }
  serializer.farm_kml.kml.geometry_wrapper:
    class: Drupal\farm_kml\Normalizer\KmlNormalizer
    arguments: ['@geofield.geophp']
    tags:
      - { name: normalizer, priority: 10 }