Laravel5.5でSocialiteに含まれていないLINE認証

<?php

namespace App\Socialite;

use Laravel\Socialite\Two\AbstractProvider;
use Laravel\Socialite\Two\ProviderInterface;
use Laravel\Socialite\Two\User;

class LineProvider extends AbstractProvider implements ProviderInterface
{
    protected function getAuthUrl($state)
    {
        return $this->buildAuthUrlFromBase('https://access.line.me/dialog/oauth/weblogin', $state);

    }
    protected function getTokenUrl()
    {

        return 'https://api.line.me/v2/oauth/accessToken/';

    }
    public function getAccessTokenResponse($code)
    {


        $response = $this->getHttpClient()->post($this->getTokenUrl(), [
            'headers' => ['Accept' => 'application/json'],
            'form_params' => [
                'grant_type' => 'authorization_code',
                'code' => $code,
                'redirect_uri' => $this->redirectUrl,
                'client_id' => $this->clientId,
                'client_secret' => $this->clientSecret
            ],
        ]);

        return json_decode($response->getBody(), true);
    }
    protected function getUserByToken($token)
    {

        $response = $this->getHttpClient()->get('https://api.line.me/v2/profile', [
            'headers' => [
                'Authorization' => 'Bearer '.$token,
            ],
        ]);

        return json_decode($response->getBody(), true);
    }

    protected function mapUserToObject(array $user)
    {
        return (new User())->setRaw($user)->map([
            'id' => $user['userId'],
            'name' => $user['displayName'],
            'pictureUrl' => $user['pictureUrl'],
        ]);
    }
}