Björn Brala
--- a/modules/jsonapi_defaults/src/JsonapiDefaults.php 0 → 100644
+++ b/modules/jsonapi_defaults/src/JsonapiDefaults.php 0 → 100644
+class JsonapiDefaults implements JsonapiDefaultsInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getResourceConfigFromRequest(Request $request, ResourceType $resourceType = NULL): ?JsonapiResourceConfig {
+    $resourceType = !$resourceType ? $request->get(Routes::RESOURCE_TYPE_KEY) : $resourceType;
+
+    if ($resourceType instanceof ConfigurableResourceType) {
+      $relatedField = $request->attributes->get('_on_relationship')
+        ? NULL
+        : $request->attributes->get('related');
+        $resourceType = static::correctResourceTypeOnRelated($relatedField, $resourceType);
+
+      if (
+          $resourceType instanceof ConfigurableResourceType
--- a/modules/jsonapi_defaults/src/Controller/EntityResource.php
+++ b/modules/jsonapi_defaults/src/Controller/EntityResource.php
+   *   The entity type manager.
+   * @param \Drupal\Core\Entity\EntityFieldManagerInterface $field_manager
+   *   The entity type field manager.
+   * @param \Drupal\jsonapi\ResourceType\ResourceTypeRepositoryInterface $resource_type_repository
+   *   The JSON:API resource type repository.
+   * @param \Drupal\Core\Render\RendererInterface $renderer
+   *   The renderer.
+   * @param \Drupal\Core\Entity\EntityRepositoryInterface $entity_repository
+   *   The entity repository.
+   * @param \Drupal\jsonapi\IncludeResolver $include_resolver
+   *   The include resolver.
+   * @param \Drupal\jsonapi\Access\EntityAccessChecker $entity_access_checker
+   *   The JSON:API entity access checker.
+   * @param \Drupal\jsonapi\Context\FieldResolver $field_resolver
+   *   The JSON:API field resolver.
+   * @param \Symfony\Component\Serializer\SerializerInterface|\Symfony\Component\Serializer\Normalizer\DenormalizerInterface $serializer