test1/public/drupal/modules/migrate_plus/migrate_plus...

<?php

/**
 * @file
 * Install, update, and uninstall functions for migrate_plus.
 */

/**
 * Converts 8.0.x core migration entities to 8.1.x migrate_plus entities.
 */
function migrate_plus_update_8100() {
  // We cannot use the configration entity system directly, because the entity
  // type migrate.migration.* no longer exists - we must directly manipulate
  // the config table.
  $database = \Drupal::database();
  $migration_config = $database->select('config', 'c')
    ->fields('c', ['name', 'data'])
    ->condition('name', 'migrate.migration.%', 'LIKE')
    ->execute();
  foreach ($migration_config as $migration) {
    $data = unserialize($migration->data);
    if (isset($data['third_party_settings']['migrate_plus']['migration_group'])) {
      $data['migration_group'] = $data['third_party_settings']['migrate_plus']['migration_group'];
      unset($data['third_party_settings']['migrate_plus']);
      if (empty($data['third_party_settings'])) {
        unset($data['third_party_settings']);
      }
      $new_name = str_replace('migrate.migration.', 'migrate_plus.migration.', $migration->name);
      $database->update('config')
        ->fields([
          'name' => $new_name,
          'data' => serialize($data),
        ])
        ->condition('name', $migration->name)
        ->execute();
    }
  }
}