Laravel dingo Transformers问题

// AuthenticateTransformers
    public function transform(Customer $customer)
    {
        return [
            'id' => $customer['id'],
            'name' => $customer['name'],
            'username' => $customer['username'],
            'secret' => $customer['secret'],
            'startDate' => $customer['startDate'],
            'endDate' => $customer['endDate'],
            'token' => $customer['token'],
        ];
    }

    /**
     * @param \App\Models\Customer $customer
     *
     * @return array
     */
    public function getAuthenticatedUser(Customer $customer)
    {
        return [
            'id' => $customer['id'],
            'name' => $customer['name'],
            'username' => $customer['username'],
            'secret' => $customer['secret'],
            'startDate' => $customer['startDate'],
            'endDate' => $customer['endDate'],
        ];
    }

// 回调
return $this->item($customer, new AuthenticateTransformers, function ($resource, $fractal) {

            $fractal->setSerializer(new CustomSerializer());

});

查阅了一些文档，new Transformers的时候默认transform方法，

但是不能一个文件就为这一个方法而存吧，
我怎么在回调的时候想指向自定义的方法比如getAuthenticatedUser这个方法