reverted:
--- b/core/modules/migrate_drupal_ui/src/Batch/MigrateUpgradeBatchBase.php
+++ /dev/null
@@ -1,116 +0,0 @@
-<?php
-
-namespace Drupal\migrate_drupal_ui\Batch;
-
-use Drupal\migrate\Plugin\MigrationInterface;
-use Drupal\migrate\Event\MigrateIdMapMessageEvent;
-use Drupal\migrate\Event\MigrateMapDeleteEvent;
-use Drupal\migrate\Event\MigrateMapSaveEvent;
-use Drupal\migrate\Event\MigratePostRowSaveEvent;
-use Drupal\migrate\Event\MigrateRowDeleteEvent;
-
-/**
- * Runs a single migration batch.
- */
-abstract class MigrateUpgradeBatchBase {
-
-  /**
-   * Maximum number of previous messages to display.
-   */
-  const MESSAGE_LENGTH = 20;
-
-  /**
-   * The processed items for one batch of a given migration.
-   *
-   * @var int
-   */
-  static $numProcessed = 0;
-
-  /**
-   * Ensure we only add the listeners once per request.
-   *
-   * @var bool
-   */
-  protected static $listenersAdded = FALSE;
-
-  /**
-   * The maximum length in seconds to allow processing in a request.
-   *
-   * @see self::run()
-   *
-   * @var int
-   */
-  protected static $maxExecTime;
-
-  /**
-   * MigrateMessage instance to capture messages during the migration process.
-   *
-   * @var \Drupal\migrate_drupal_ui\Batch\MigrateMessageCapture
-   */
-  protected static $messages;
-
-  /**
-   * Reacts to item import.
-   *
-   * @param \Drupal\migrate\Event\MigratePostRowSaveEvent $event
-   *   The post-save event.
-   */
-  public static function onPostRowSave(MigratePostRowSaveEvent $event) {
-    // We want to interrupt this batch and start a fresh one.
-    if ((time() - REQUEST_TIME) > static::$maxExecTime) {
-      $event->getMigration()->interruptMigration(MigrationInterface::RESULT_INCOMPLETE);
-    }
-  }
-
-  /**
-   * Reacts to item deletion.
-   *
-   * @param \Drupal\migrate\Event\MigrateRowDeleteEvent $event
-   *   The post-save event.
-   */
-  public static function onPostRowDelete(MigrateRowDeleteEvent $event) {
-    // We want to interrupt this batch and start a fresh one.
-    if ((time() - REQUEST_TIME) > static::$maxExecTime) {
-      $event->getMigration()->interruptMigration(MigrationInterface::RESULT_INCOMPLETE);
-    }
-  }
-
-  /**
-   * Counts up any map save events.
-   *
-   * @param \Drupal\migrate\Event\MigrateMapSaveEvent $event
-   *   The map event.
-   */
-  public static function onMapSave(MigrateMapSaveEvent $event) {
-    static::$numProcessed++;
-  }
-
-  /**
-   * Counts up any map delete events.
-   *
-   * @param \Drupal\migrate\Event\MigrateMapDeleteEvent $event
-   *   The map event.
-   */
-  public static function onMapDelete(MigrateMapDeleteEvent $event) {
-    static::$numProcessed++;
-  }
-
-  /**
-   * Displays any messages being logged to the ID map.
-   *
-   * @param \Drupal\migrate\Event\MigrateIdMapMessageEvent $event
-   *   The message event.
-   */
-  public static function onIdMapMessage(MigrateIdMapMessageEvent $event) {
-    if ($event->getLevel() == MigrationInterface::MESSAGE_NOTICE || $event->getLevel() == MigrationInterface::MESSAGE_INFORMATIONAL) {
-      $type = 'status';
-    }
-    else {
-      $type = 'error';
-    }
-    $source_id_string = implode(',', $event->getSourceIdValues());
-    $message = t('Source ID @source_id: @message', ['@source_id' => $source_id_string, '@message' => $event->getMessage()]);
-    static::$messages->display($message, $type);
-  }
-
-}