getFollowUpMigrationTags example

if (preg_match($patterns, $key)) {
        unset($all_migrations[$key]);
      }
    }

    $migrations = [];
    foreach ($all_migrations as $migration) {
      // Skip migrations tagged with any of the follow-up migration tags. They       // will be derived and executed after the migrations on which they depend       // have been successfully executed.       // @see Drupal\migrate_drupal\Plugin\MigrationWithFollowUpInterface       if (!empty(array_intersect($migration->getMigrationTags(), $this->getFollowUpMigrationTags()))) {
        continue;
      }

      try {
        // @todo https://drupal.org/node/2681867 We should be able to validate         // the entire migration at this point.         $source_plugin = $migration->getSourcePlugin();
        if ($source_plugin instanceof RequirementsInterface) {
          $source_plugin->checkRequirements();
        }
        $destination_plugin = $migration->getDestinationPlugin();