diff -u b/core/modules/migrate_drupal/src/Annotation/MigrateField.php b/core/modules/migrate_drupal/src/Annotation/MigrateField.php
--- b/core/modules/migrate_drupal/src/Annotation/MigrateField.php
+++ b/core/modules/migrate_drupal/src/Annotation/MigrateField.php
@@ -49,7 +49,7 @@
    *
    * @var int[]
    */
-  public $core = [];
+  public $core;
 
   /**
    * Identifies the system providing the data the field plugin will read.
diff -u b/core/modules/migrate_drupal/src/Plugin/MigrateCckFieldPluginManager.php b/core/modules/migrate_drupal/src/Plugin/MigrateCckFieldPluginManager.php
--- b/core/modules/migrate_drupal/src/Plugin/MigrateCckFieldPluginManager.php
+++ b/core/modules/migrate_drupal/src/Plugin/MigrateCckFieldPluginManager.php
@@ -20,39 +20 @@
-class MigrateCckFieldPluginManager extends MigrateFieldPluginManager implements MigrateCckFieldPluginManagerInterface {
-
-  /**
-   * The default version of core to use for cck field plugins.
-   *
-   * These plugins were initially only built and used for Drupal 6 cck fields.
-   * Having been extended for Drupal 7 with a "core" annotation, we fall back to
-   * Drupal 6 where none exists.
-   */
-  const DEFAULT_CORE_VERSION = 6;
-
-  /**
-   * {@inheritdoc}
-   */
-  public function getPluginIdFromFieldType($field_type, array $configuration = [], MigrationInterface $migration = NULL) {
-    $core = static::DEFAULT_CORE_VERSION;
-    if (!empty($configuration['core'])) {
-      $core = $configuration['core'];
-    }
-    elseif (!empty($migration->getPluginDefinition()['migration_tags'])) {
-      foreach ($migration->getPluginDefinition()['migration_tags'] as $tag) {
-        if ($tag == 'Drupal 7') {
-          $core = 7;
-        }
-      }
-    }
-
-    $definitions = $this->getDefinitions();
-    foreach ($definitions as $plugin_id => $definition) {
-      if (in_array($core, $definition['core'])) {
-        if (array_key_exists($field_type, $definition['type_map']) || $field_type === $plugin_id) {
-          return $plugin_id;
-        }
-      }
-    }
-    throw new PluginNotFoundException($field_type);
-  }
-
-}
+class MigrateCckFieldPluginManager extends MigrateFieldPluginManager implements MigrateCckFieldPluginManagerInterface {}
diff -u b/core/modules/migrate_drupal/src/Plugin/MigrateFieldPluginManager.php b/core/modules/migrate_drupal/src/Plugin/MigrateFieldPluginManager.php
--- b/core/modules/migrate_drupal/src/Plugin/MigrateFieldPluginManager.php
+++ b/core/modules/migrate_drupal/src/Plugin/MigrateFieldPluginManager.php
@@ -67,7 +67,7 @@
     }
   }
 
- /**
+  /**
    * {@inheritdoc}
    */
   public function getSourceModule($definition) {
diff -u b/core/modules/migrate_drupal/src/Plugin/migrate/field/NodeReference.php b/core/modules/migrate_drupal/src/Plugin/migrate/field/NodeReference.php
--- b/core/modules/migrate_drupal/src/Plugin/migrate/field/NodeReference.php
+++ b/core/modules/migrate_drupal/src/Plugin/migrate/field/NodeReference.php
@@ -4,7 +4,7 @@
 
 use Drupal\migrate\Plugin\MigrationInterface;
 
-/*3*
+/**
  * @MigrateField(
  *   id = "nodereference",
  *   core = {6},