Support entities that are neither content nor config entites

Modification of https://www.drupal.org/files/issues/2019-05-29/3042467-31.patch that fixes PHP Exception for pattern in deprecation notice. See corresponding patch at https://www.drupal.org/project/drupal/issues/3042467#comment-13917262

core/modules/jsonapi/src/Controller/EntityResource.php

@@ -8,7 +8,6 @@
 use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Cache\CacheableResponseInterface;
 use Drupal\Core\Config\Entity\ConfigEntityInterface;
-use Drupal\Core\Entity\ContentEntityInterface;
 use Drupal\Core\Entity\EntityFieldManagerInterface;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\EntityRepositoryInterface;
@@ -1089,8 +1088,9 @@ protected function respondWithCollection(ResourceObjectData $primary_data, Data
    *   types.
    */
   protected function updateEntityField(ResourceType $resource_type, EntityInterface $origin, EntityInterface $destination, $field_name) {
-    // The update is different for configuration entities and content entities.
-    if ($origin instanceof ContentEntityInterface && $destination instanceof ContentEntityInterface) {
+    // The update is different for configuration entities and fieldable
+    // entities.
+    if ($origin instanceof FieldableEntityInterface && $destination instanceof FieldableEntityInterface) {
       // First scenario: both are content entities.
       $field_name = $resource_type->getInternalName($field_name);
       $destination_field_list = $destination->get($field_name);