update.source.schema.yml in Drupal 9

core/modules/update/config/schema/update.source.schema.yml

File

core/modules/update/config/schema/update.source.schema.yml

# Schema for the migration source plugins.

migrate.source.update_settings:
  type: migrate_source_sql
  label: 'Drupal update settings'
  mapping:
    variables:
      type: sequence
      label: 'Variables'
      sequence:
        type: string
        label: 'Variable'