protected function createDefaultJwtAccessTokenStorage()
    {
        if (!isset($this->storages['public_key'])) {
            throw new \LogicException('You must supply a storage object implementing OAuth2\Storage\PublicKeyInterface to use crypto tokens');
        }
        $tokenStorage = null;
        if (!empty($this->config['store_encrypted_token_string']) && isset($this->storages['access_token'])) {
            $tokenStorage = $this->storages['access_token'];
        }
        // wrap the access token storage as required.
        return new JwtAccessTokenStorage($this->storages['public_key'], $tokenStorage);
    }