metrc-1.0.x-dev/modules/metrc_migrate/metrc_migrate.routing.yml

entity.migration.process.historical:
  path: '/admin/structure/migrate/manage/{migration_group}/migrations/{migration}/historical'
  defaults:
    _controller: '\Drupal\metrc_migrate\Controller\MigrationController::historical'
    _title: 'Historical Data Load'
    _migrate_group: true
  requirements:
    _permission: 'administer migrations'
  options:
    parameters:
      migration:
        type: entity:migration
      migration_group:
        type: entity:migration_group