I get Class 'Mautic\\Auth\\ApiAuth' not found since updated

Since we updated to the current Mautic Version 4.2.0 I get this error:

Uncaught Error: Class 'Mautic\\Auth\\ApiAuth' not found

I created a new server from the scratch and I get the same error. We did this conector, which worked fine until now:

<?php
  include 'vendor/autoload.php';
  use Mautic\Auth\ApiAuth;
  use Mautic\MauticApi;
//define function name  

  session_start();

  $settings = array(
      'userName'         => 'user',
      'password'         => 'pass',
  );

  $initAuth   = new ApiAuth();
  $auth       = $initAuth->newAuth($settings, 'BasicAuth');

  try{
    if ($auth) {
      $api        = new MauticApi();
      $contactApi = $api->newApi("contacts", $auth, 'https://mautic/api/');
      file_put_contents('conector.log', 'REQUEST: '.print_r($_REQUEST,true),FILE_APPEND);
            if($_REQUEST['action'] == "new"){
                $firstname = $_REQUEST['firstname'];
                $lastname = $_REQUEST['lastname'];
                $email = $_REQUEST['email'];
                $company = $_REQUEST['company'];
                $country = $_REQUEST['country'];
                $preferred_locale = strtolower($_REQUEST['preferred_locale']);
                $birthdate = $_REQUEST['birthdate'];
                $gender = $_REQUEST['gender'];
                $crm_source = $_REQUEST['crm_source'];

       $data = array(
        'firstname'     =>      $firstname,
        'lastname'      =>      $lastname,
        'email'     =>  $email,
        'company'       =>      $company,
        'country'       =>      $country,
        'preferred_locale'      =>      $preferred_locale,
        'birthdate'      =>      $birthdate,
        'gender'        =>      $gender,
        'crm_source'    =>      $crm_source
        );


        $contact = $contactApi->create($data);

        file_put_contents('conector.log', 'CONTACT API '.print_r($contact,true),FILE_APPEND | LOCK_EX);
        $idcontacto = $contact['contact']['id'];
 }else if($_REQUEST['action'] == "delete"){
        $contact = $contactApi->delete($_REQUEST['idContact']);
      }

    } else {
                echo "Error!";
    }
  } catch (Exception $e) {
        echo "Mautic not connected!";
  }
?>


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Start with the supplied PHP connector and its vendor/autoload.php include, then reproduce the missing Mautic\Auth\ApiAuth error against Mautic 4.2.0. Check how the API library exposes authentication and compare that with the connector's ApiAuth and MauticApi usage. Done means the connector's authentication path works on a fresh setup or the incompatibility is clearly documented.