Class not found Error, problem with namespaces

With the appearance of namespaces in CI4, the location of certain libraries or helpers has become rather conditionaly.

Let's say you want to make a helper class and place it in the app/Helper directory

in file app/Helpers/Php2jquery.php

PHP Code:

<?php

namespace App\Helpers;

class Php2jquery {
    function phpArrayToJqueryParam($param, $indent = 0, $object = "", $wrapfunction = "") {
        return 'test';
    }
} 


in file app/Controllers/Test.php

PHP Code:

<?php

namespace App\Controllers;

use App\Helpers\Php2jquery;

class Test extends BaseController {

    public function index() {
        $jqueryparam = new Php2jquery();

        $data[‘jqueryobject’] = $jqueryparam->php_array_to_jquery_param($param, 4, "new FWDRAP", "FWDRAPUtils.onReady(function(){" );

        return view('index', $data);
    }
} 


Please note that the file and class name starts with a capital letter as recommended in the manual