Issue #2282627 by yched, swentel: Remove field_uuid from field instance config records.

core/modules/field/config/schema/field.schema.yml

@@ -58,9 +58,6 @@ field.instance.*.*.*:
     label:
       type: label
       label: 'Label'
-    field_uuid:
-      type: string
-      label: 'Field UUID'
     field_name:
       type: string
       label: 'Field name'

core/modules/field/src/Entity/FieldInstanceConfig.php

@@ -54,13 +54,6 @@ class FieldInstanceConfig extends ConfigEntityBase implements FieldInstanceConfi
    */
   public $field_name;
 
-  /**
-   * The UUID of the field attached to the bundle by this instance.
-   *
-   * @var string
-   */
-  public $field_uuid;
-
   /**
    * The name of the entity type the instance is attached to.
    *
@@ -193,7 +186,7 @@ class FieldInstanceConfig extends ConfigEntityBase implements FieldInstanceConfi
   public $deleted = FALSE;
 
   /**
-   * The field ConfigEntity object corresponding to $field_uuid.
+   * The field ConfigEntity object this is an instance of.
    *
    * @var \Drupal\field\Entity\FieldConfig
    */
@@ -306,10 +299,7 @@ public function toArray() {
   public function postCreate(EntityStorageInterface $storage) {
     // Validate that we have a valid field for this instance. This throws an
     // exception if the field is invalid.
-    $field = $this->getFieldStorageDefinition();
-
-    // Make sure the field_uuid is populated.
-    $this->field_uuid = $field->uuid();
+    $this->getFieldStorageDefinition();
 
     // 'Label' defaults to the field name (mostly useful for field instances
     // created in tests).
@@ -346,7 +336,7 @@ public function preSave(EntityStorageInterface $storage) {
       if ($this->bundle != $this->original->bundle && empty($this->bundle_rename_allowed)) {
         throw new FieldException("Cannot change an existing instance's bundle.");
       }
-      if ($this->field_uuid != $this->original->field_uuid) {
+      if ($field->uuid() != $this->original->getFieldStorageDefinition()->uuid()) {
         throw new FieldException("Cannot change an existing instance's field.");
       }
       // Set the default instance settings.
@@ -405,6 +395,7 @@ public static function preDelete(EntityStorageInterface $storage, array $instanc
       if (!$instance->deleted) {
         $config = $instance->toArray();
         $config['deleted'] = TRUE;
+        $config['field_uuid'] = $instance->getFieldStorageDefinition()->uuid();
         $deleted_instances[$instance->uuid()] = $config;
       }
     }
@@ -440,7 +431,7 @@ public static function postDelete(EntityStorageInterface $storage, array $instan
       $field = $instance->getFieldStorageDefinition();
       if (!$instance->deleted && empty($instance->noFieldDelete) && !$instance->isUninstalling() && count($field->getBundles()) == 0) {
         // Key by field UUID to avoid deleting the same field twice.
-        $fields_to_delete[$instance->field_uuid] = $field;
+        $fields_to_delete[$field->uuid()] = $field;
       }
     }
     if ($fields_to_delete) {

core/modules/field/src/FieldInstanceConfigStorage.php

@@ -143,7 +143,8 @@ public function loadByProperties(array $conditions = array()) {
             break;
 
           case 'field_id':
-            $checked_value = $instance->field_uuid;
+          case 'field_uuid':
+            $checked_value = $field->uuid();
             break;
 
           case 'uuid';

core/modules/field/tests/modules/field_test_config/staging/field.instance.entity_test.entity_test.field_test_import_staging.yml

 id: entity_test.entity_test.field_test_import_staging
 uuid: ea711065-6940-47cd-813d-618f64095481
 langcode: und
-field_uuid: 0bf654cc-f14a-4881-b94c-76959e47466b
 field_name: field_test_import_staging
 entity_type: entity_test
 bundle: entity_test

core/modules/field/tests/modules/field_test_config/staging/field.instance.entity_test.test_bundle.field_test_import_staging_2.yml

 id: entity_test.test_bundle.field_test_import_staging_2
 uuid: f07794a2-d7cc-45b6-b40d-13cf021b5552
 langcode: und
-field_uuid: 2165d9aa-9a0c-41a1-be02-2a49f3405c00
 field_name: field_test_import_staging_2
 entity_type: entity_test
 bundle: test_bundle

core/modules/field/tests/modules/field_test_config/staging/field.instance.entity_test.test_bundle_2.field_test_import_staging_2.yml

 id: entity_test.test_bundle_2.field_test_import_staging_2
 uuid: 49d6dd19-5097-443d-8f00-fc79525bebce
 langcode: und
-field_uuid: 2165d9aa-9a0c-41a1-be02-2a49f3405c00
 field_name: field_test_import_staging_2
 entity_type: entity_test
 bundle: test_bundle_2

core/modules/field/tests/src/FieldInstanceConfigEntityUnitTest.php

@@ -150,7 +150,6 @@ public function testToArray() {
       'uuid' => NULL,
       'status' => TRUE,
       'langcode' => LanguageInterface::LANGCODE_NOT_SPECIFIED,
-      'field_uuid' => NULL,
       'field_name' => 'field_test',
       'entity_type' => 'test_entity_type',
       'bundle' => 'test_bundle',