Issue with appDirect Subscription Order Form Validation

Question

I am trying to implement Form Validation for appDirect Subscription Order

Below is the subscription create notification url and is working fine (Please not the url is not contain any '.php').

http://myhost.com/project/public/createsubscription?token=%7btoken%7d&async=true

configured the form validation url in same format as above but it is not working. Below is the url

http://myhost.com/project/public/productsettingsvalidation

my code in routes.php is as follows

$app->get('productsettingsvalidation','App\Http\Controllers\ProductSettingsController@index'); 

the ProductSettingsController code is as follows

<?php namespace App\Http\Controllers;

use App\Http\Controllers\Controller;
use Illuminate\Http\Request;
use App\Library\ProcessRequest;

class ProductSettingsController extends Controller
{

     /**    
     * Hold the default request.
     */
    protected $request;


    /** 
     * Hold the default request.
     */
    protected $process;


    /**
     * Create a new controller instance.
     *
     * @return void
     */

    public function __construct(Request $request, ProcessRequest $process)
    {
        $this->request = $request;      
        $this->process = $process;
    } 


    public function index(){
        // This will write into a file
        $this->process->wtrite_log(" new requst");      
    }   
}

It is not write anything into the log. thus the above url itself is not working. If this url is changed to http://myhost.com/project/public/productsettingsvalidation.php, then it is working fine.

We think it is more related to URL structure. Can you please advice on this issue.