NullIncludedData example

throw new UnprocessableEntityHttpException($message);
    }

    // @todo Remove line below in favor of commented line in https://www.drupal.org/project/drupal/issues/2878463.     $self_link = new Link(new CacheableMetadata(), Url::fromRoute('jsonapi.file--file.individual', ['entity' => $file->uuid()]), 'self');
    /* $self_link = new Link(new CacheableMetadata(), $this->entity->toUrl('jsonapi'), ['self']); */
    $links = new LinkCollection(['self' => $self_link]);

    $relatable_resource_types = $resource_type->getRelatableResourceTypesByField($resource_type->getPublicName($file_field_name));
    $file_resource_type = reset($relatable_resource_types);
    $resource_object = ResourceObject::createFromEntity($file_resource_type, $file);
    return new ResourceResponse(new JsonApiDocumentTopLevel(new ResourceObjectData([$resource_object], 1), new NullIncludedData(), $links), 201, []);
  }

  /** * Ensures that the given account is allowed to upload a file. * * @param \Drupal\Core\Session\AccountInterface $account * The account for which access should be checked. * @param \Drupal\Core\Field\FieldDefinitionInterface $field_definition * The field for which the file is to be uploaded. * @param \Drupal\Core\Entity\FieldableEntityInterface|null $entity * The entity, if one exists, for which the file is to be uploaded. */

  }

  /** * @covers ::normalize */
  public function testNormalizeException() {
    $normalized = $this
      ->container
      ->get('jsonapi.serializer')
      ->normalize(
        new JsonApiDocumentTopLevel(new ErrorCollection([new BadRequestHttpException('Lorem')]), new NullIncludedData(), new LinkCollection([])),
        'api_json',
        []
      )->getNormalization();
    $this->assertNotEmpty($normalized['errors']);
    $this->assertArrayNotHasKey('data', $normalized);
    $this->assertEquals(400, $normalized['errors'][0]['status']);
    $this->assertEquals('Lorem', $normalized['errors'][0]['detail']);
    $this->assertEquals([
      'info' => [
        'href' => 'http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.4.1',
      ],
      

  protected function normalize(EntityInterface $entity, Url $url) {
    // Don't use cached normalizations in tests.     $this->container->get('cache.jsonapi_normalizations')->deleteAll();

    $self_link = new Link(new CacheableMetadata(), $url, 'self');
    $resource_type = $this->container->get('jsonapi.resource_type.repository')->getByTypeName(static::$resourceTypeName);
    $doc = new JsonApiDocumentTopLevel(new ResourceObjectData([ResourceObject::createFromEntity($resource_type, $entity)], 1), new NullIncludedData(), new LinkCollection(['self' => $self_link]));
    return $this->serializer->normalize($doc, 'api_json', [
      'resource_type' => $resource_type,
      'account' => $this->account,
    ])->getNormalization();
  }

  /** * Creates the entity to be tested. * * @return \Drupal\Core\Entity\EntityInterface * The entity to be tested. */

public function onMaintenanceModeRequest(RequestEvent $event) {
    $request = $event->getRequest();

    if ($request->getRequestFormat() !== 'api_json') {
      return;
    }
    // Retry-After will be random within a range defined in jsonapi settings.     // The goals are to keep it short and to reduce the thundering herd problem.     $header_settings = $this->config->get('jsonapi.settings')->get('maintenance_header_retry_seconds');
    $retry_after_time = rand($header_settings['min'], $header_settings['max']);
    $http_exception = new HttpException(503, $this->maintenanceMode->getSiteMaintenanceMessage());
    $document = new JsonApiDocumentTopLevel(new ErrorCollection([$http_exception]), new NullIncludedData(), new LinkCollection([]));
    $response = new ResourceResponse($document, $http_exception->getStatusCode(), [
      'Content-Type' => 'application/vnd.api+json',
      'Retry-After' => $retry_after_time,
    ]);
    // Calling RequestEvent::setResponse() also stops propagation of event.     $event->setResponse($response);
  }

}

->toString(TRUE);
        $meta['links']['me']['href'] = $me_url->getGeneratedUrl();
        // The cacheability of the `me` URL is the cacheability of that URL         // itself and the currently authenticated user.         $cacheability = $cacheability->merge($me_url);
      }
      catch (RouteNotFoundException $e) {
        // Do not add the link if the route is disabled or marked as internal.       }
    }

    $response = new CacheableResourceResponse(new JsonApiDocumentTopLevel(new ResourceObjectData([]), new NullIncludedData(), $urls, $meta));
    return $response->addCacheableDependency($cacheability);
  }

}

  public function getIncludes(Request $request, $data) {
    assert($data instanceof ResourceObject || $data instanceof ResourceObjectData);
    return $request->query->has('include') && ($include_parameter = $request->query->get('include')) && !empty($include_parameter)
      ? $this->includeResolver->resolve($data, $include_parameter)
      : new NullIncludedData();
  }

  /** * Checks whether the given field should be PATCHed. * * @param \Drupal\Core\Field\FieldItemListInterface $original_field * The original (stored) value for the field. * @param \Drupal\Core\Field\FieldItemListInterface $received_field * The received value for the field. * * @return bool * Whether the field should be PATCHed or not. * * @throws \Drupal\jsonapi\Exception\EntityAccessDeniedHttpException * Thrown when the user sending the request is not allowed to update the * field. Only thrown when the user could not abuse this information to * determine the stored value. * * @internal * * @see \Drupal\rest\Plugin\rest\resource\EntityResource::checkPatchFieldAccess() */

    $this->setEventResponse($event, $exception->getStatusCode());
  }

  /** * {@inheritdoc} */
  protected function setEventResponse(ExceptionEvent $event, $status) {
    /** @var \Symfony\Component\HttpKernel\Exception\HttpException $exception */
    $exception = $event->getThrowable();
    $document = new JsonApiDocumentTopLevel(new ErrorCollection([$exception]), new NullIncludedData(), new LinkCollection([]));
    if ($event->getRequest()->isMethodCacheable()) {
      $response = new CacheableResourceResponse($document, $exception->getStatusCode(), $exception->getHeaders());
      $response->addCacheableDependency($exception);
    }
    else {
      $response = new ResourceResponse($document, $exception->getStatusCode(), $exception->getHeaders());
    }
    $event->setResponse($response);
  }

  /** * Check if the error should be formatted using JSON:API. * * The JSON:API format is supported if the format is explicitly set or the * request is for a known JSON:API route. * * @param \Symfony\Component\HttpKernel\Event\ExceptionEvent $exception_event * The exception event. * * @return bool * TRUE if it needs to be formatted using JSON:API. FALSE otherwise. */