signaturehelpercreate.php

См. документацию.

<?php
namespace Bitrix\Main\UserField;
 
class SignatureHelperCreate extends SignatureHelper
{
    protected static function getSignatureParam(array $fieldParam)
    {
        return serialize(array(
            'ENTITY_ID' => strval($fieldParam['ENTITY_ID']),
        ));
    }
}