invoiceninja/app/Models/Gateway.php

<?php
/**
 * Invoice Ninja (https://invoiceninja.com)
 *
 * @link https://github.com/invoiceninja/invoiceninja source repository
 *
 * @copyright Copyright (c) 2019. Invoice Ninja LLC (https://invoiceninja.com)
 *
 * @license https://opensource.org/licenses/AAL
 */

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Omnipay\Omnipay;

class Gateway extends StaticModel
{

    /**
     * @return mixed
     */
    public function getFields()
    {

        if ($this->isCustom()) 
        {
            return [
                'name' => '',
                'text' => '',
            ];
        } else 
        {
            return Omnipay::create($this->provider)->getDefaultParameters();
        }

    }

    /**
     * Test if gateway is custom
     * @return boolean TRUE|FALSE
     */
    public function isCustom() :bool
    {

        return in_array($this->id, [62, 67, 68]); //static table ids of the custom gateways

    }

}