Fix inline_entity_form plugin not found error in upgrade_d7_field_instance_widget_settings migration.

fix-inline_entity_form-error-in-d7_field_instance_widget_settings-migration.patch

diff --git a/core/modules/field/src/Plugin/migrate/field/d7/EntityReference.php b/core/modules/field/src/Plugin/migrate/field/d7/EntityReference.php
index bebb360d63..321d1f856a 100644
--- a/core/modules/field/src/Plugin/migrate/field/d7/EntityReference.php
+++ b/core/modules/field/src/Plugin/migrate/field/d7/EntityReference.php
@@ -32,4 +32,15 @@ public function getFieldFormatterMap() {
     ];
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getFieldWidgetMap() {
+    $map = parent::getFieldWidgetMap() + [
+      'inline_entity_form_single' => 'inline_entity_form_simple',
+      'inline_entity_form' => 'inline_entity_form_complex',
+    ];
+    return $map;
+  }
+
 }