trait DeveloperAppFormTrait in Apigee Edge 8

trait DeveloperAppFormTrait {

  /**
   * {@inheritdoc}
   */
  public static function appExists(string $name, array $element, FormStateInterface $form_state) : bool {

    // Do not validate if app name is not set.
    if ($name === '') {
      return FALSE;
    }

    // Return TRUE if developer account has not been found for this Drupal user.
    // TODO Make sure that DeveloperAppCreateEditFormForDeveloper can be
    // used only if the Drupal user in the route has a developer account
    // in Apigee Edge.
    if ($form_state
      ->getValue('owner') === NULL) {
      return TRUE;
    }

    // We use the developer app controller factory here instead of entity
    // query to reduce the number API calls. (Entity query may load all
    // developers to return whether the given developer has an app with
    // the provided name already.)

    /** @var \Drupal\apigee_edge\Entity\Controller\DeveloperAppControllerFactoryInterface $factory */
    $factory = \Drupal::service('apigee_edge.controller.developer_app_controller_factory');
    $app = TRUE;
    try {
      $app = $factory
        ->developerAppController($form_state
        ->getValue('owner'))
        ->load($name);
    } catch (ApiException $exception) {
      if ($exception instanceof ClientErrorException && $exception
        ->getEdgeErrorCode() === 'developer.service.AppDoesNotExist') {
        $app = FALSE;
      }
      else {

        // Fail safe, return TRUE in case of an API communication error or an
        // unexpected response.
        $context = [
          '%app_name' => $name,
          '%owner' => $form_state
            ->getValue('owner'),
        ];
        $context += Error::decodeException($exception);
        \Drupal::logger('apigee_edge')
          ->error("Unable to properly validate an app name's uniqueness. App name: %app_name. Owner: %owner. @message %function (line %line of %file). <pre>@backtrace_string</pre>", $context);
      }
    }
    return (bool) $app;
  }

  /**
   * {@inheritdoc}
   */
  protected function appEntityDefinition() : EntityTypeInterface {
    return $this
      ->getEntityTypeManager()
      ->getDefinition('developer_app');
  }

  /**
   * {@inheritdoc}
   */
  protected function appOwnerEntityDefinition() : EntityTypeInterface {
    return $this
      ->getEntityTypeManager()
      ->getDefinition('developer');
  }

  /**
   * {@inheritdoc}
   */
  protected function appCredentialLifeTime() : int {
    $config_name = 'apigee_edge.developer_app_settings';
    $config = method_exists($this, 'config') ? $this
      ->config($config_name) : \Drupal::config($config_name);
    return $config
      ->get('credential_lifetime');
  }

  /**
   * Allows to access to the injected entity type manager.
   *
   * @return \Drupal\Core\Entity\EntityTypeManagerInterface
   *   The entity type manager.
   */
  private function getEntityTypeManager() : EntityTypeManagerInterface {
    if (property_exists($this, 'entityTypeManager') && $this->entityTypeManager instanceof EntityTypeManagerInterface) {
      return $this->entityTypeManager;
    }
    return \Drupal::entityTypeManager();
  }

  /**
   * {@inheritdoc}
   */
  protected function apiProductList(array $form, FormStateInterface $form_state) : array {
    $email = $form_state
      ->getValue('owner') ?? $form['owner']['#value'] ?? $form['owner']['#default_value'];

    /** @var \Drupal\user\UserInterface|null $account */
    $account = user_load_by_mail($email);
    return array_filter(\Drupal::entityTypeManager()
      ->getStorage('api_product')
      ->loadMultiple(), function (ApiProductInterface $product) use ($account) {
      return $product
        ->access('assign', $account);
    });
  }

}