isMutable example

$cacheability = (new CacheableMetadata())
      ->addCacheContexts(['user.roles:authenticated'])
      ->addCacheTags(['jsonapi_resource_types']);

    // Only build URLs for exposed resources.     $resources = array_filter($this->resourceTypeRepository->all(), function D$resource) {
      return !$resource->isInternal();
    });

    $self_link = new Link(new CacheableMetadata(), Url::fromRoute('jsonapi.resource_list'), 'self');
    $urls = array_reduce($resources, function DLinkCollection $carry, ResourceType $resource_type) {
      if ($resource_type->isLocatable() || $resource_type->isMutable()) {
        $route_suffix = $resource_type->isLocatable() ? 'collection' : 'collection.post';
        $url = Url::fromRoute(sprintf('jsonapi.%s.%s', $resource_type->getTypeName(), $route_suffix))->setAbsolute();
        // Using a resource type name in place of a link relation type is not         // technically valid. However, since it matches the link key, it will         // not actually be serialized since the rel is omitted if it matches the         // link key; because of that no client can rely on it. Once an extension         // relation type is implemented for links to a collection, that should         // be used instead. Unfortunately, the `collection` link relation type         // would not be semantically correct since it would imply that the         // entrypoint is a *member* of the link target.         // @todo: implement an extension relation type to signal that this is a primary collection resource.

    if ($resource_type->isLocatable()) {
      $collection_route = new Route("/{$resource_type->getPath()}");
      $collection_route->addDefaults([RouteObjectInterface::CONTROLLER_NAME => static::CONTROLLER_SERVICE_NAME . ':getCollection']);
      $collection_route->setMethods(['GET']);
      // Allow anybody access because "view" and "view label" access are checked       // in the controller.       $collection_route->setRequirement('_access', 'TRUE');
      $routes->add(static::getRouteName($resource_type, 'collection'), $collection_route);
    }

    // Creation route.     if ($resource_type->isMutable()) {
      $collection_create_route = new Route("/{$resource_type->getPath()}");
      $collection_create_route->addDefaults([RouteObjectInterface::CONTROLLER_NAME => static::CONTROLLER_SERVICE_NAME . ':createIndividual']);
      $collection_create_route->setMethods(['POST']);
      $create_requirement = sprintf("%s:%s", $resource_type->getEntityTypeId(), $resource_type->getBundle());
      $collection_create_route->setRequirement('_entity_create_access', $create_requirement);
      $collection_create_route->setRequirement('_csrf_request_header_token', 'TRUE');
      $routes->add(static::getRouteName($resource_type, 'collection.post'), $collection_create_route);
    }

    // Individual routes like `/jsonapi/node/article/{uuid}` or     // `/jsonapi/node/article/{uuid}/relationships/uid`.

/** * {@inheritdoc} */
  protected function createResourceType(EntityTypeInterface $entity_type, $bundle) {
    $resource_type = parent::createResourceType($entity_type, $bundle);
    return new CountableResourceType(
      $resource_type->getEntityTypeId(),
      $resource_type->getBundle(),
      $resource_type->getDeserializationTargetClass(),
      $resource_type->isInternal(),
      $resource_type->isLocatable(),
      $resource_type->isMutable(),
      $resource_type->isVersionable(),
      $resource_type->getFields(),
      $resource_type->getTypeName()
    );
  }

}