BookStack/app/Auth/SocialAccount.php

<?php namespace BookStack\Auth;

use BookStack\Auth\User;
use BookStack\Model;

class SocialAccount extends Model
{

    protected $fillable = ['user_id', 'driver', 'driver_id', 'timestamps'];

    public function user()
    {
        return $this->belongsTo(User::class);
    }
}