userIsBlocked example

    if (!isset($credentials['name'])) {
      throw new BadRequestHttpException('Missing credentials.name.');
    }
    if (!isset($credentials['pass'])) {
      throw new BadRequestHttpException('Missing credentials.pass.');
    }

    $this->floodControl($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 = [];