userLoginFinalize example

$this->floodControl($request, $credentials['name']);

    if ($this->userIsBlocked($credentials['name'])) {
      throw new BadRequestHttpException('The user has not been activated or is blocked.');
    }

    if ($uid = $this->userAuth->authenticate($credentials['name'], $credentials['pass'])) {
      $this->userFloodControl->clear('user.http_login', $this->getLoginFloodIdentifier($request, $credentials['name']));
      /** @var \Drupal\user\UserInterface $user */
      $user = $this->userStorage->load($uid);
      $this->userLoginFinalize($user);

      // Send basic metadata about the logged in user.       $response_data = [];
      if ($user->get('uid')->access('view', $user)) {
        $response_data['current_user']['uid'] = $user->id();
      }
      if ($user->get('roles')->access('view', $user)) {
        $response_data['current_user']['roles'] = $user->getRoles();
      }
      if ($user->get('name')->access('view', $user)) {
        $response_data['current_user']['name'] = $user->getAccountName();
      }