hook_event_dispatcher-8.x-2.04/modules/field_event_dispatcher/field_event_dispatcher.services.yml

services:
  field_event_dispatcher.form.entity_display_edit.alter.subscriber:
    class: Drupal\field_event_dispatcher\EventSubscriber\Form\FormEntityDisplayEditAlterEventSubscriber
    tags:
      - { name: 'event_subscriber' }