mailjet plugin – extend functionnalities and reuse api

Because the template is load before the plugin, i finaly decide to add the API directly from https://github.com/mailjet/mailjet-apiv3-php-no-composer

I check the api:
https://dev.mailjet.com/guides/?php#contactslist_managemanycontacts

And build my function to send a contact to a list:

// Get the value from the plugin mailjet-for-wordpress
$apisecret = get_option('mailjet_password');
$apikey = get_option('mailjet_username');

require 'mailjet-apiv3-php-no-composer/vendor/autoload.php';

use \Mailjet\Resources;

function sendRegisterNewsletterToMailjet($params) {

$mj = new \Mailjet\Client($apikey, $apisecret);

$body = [
'Action' => "addforce",
'Contacts' => [
[
'Email' => $params['Email'],
'Properties' => [
'prénom' => $params['prénom'],
'nom' => $params['nom'],
'profession' => $params['profession'],
'structure' => $params['structure'],
]
],
]
];

$response = $mj->post(Resources::$ContactslistManagemanycontacts, ['id' => $params['ListID'], 'body' => $body]);
$response->success() && var_dump($response->getData());

wp_send_json_success($response);

}

The problem is i get this response:

{
    "success":true,
    "data":
        {
            "request":{
            "type":"application/json"
        }
    }
}

Instead of:

{
    "Count": 1,
    "Data": [
        {
            "JobID": 35800
        }
    ],
    "Total": 1
}

Any idea?