plugin-8.x-2.8/tests/modules/plugin_test_helper/plugin_test_helper.plugin_type.yml

plugin_test_helper_mock:
  label: Mock plugin
  plugin_manager_service_id: plugin.manager.plugin_test_helper.mock
  plugin_definition_decorator_class: \Drupal\plugin\PluginDefinition\ArrayPluginDefinitionDecorator
  plugin_configuration_schema_id: plugin_test_helper.plugin_configuration.plugin_test_helper_mock.[plugin_id]