leaditem.php

См. документацию.

<?
namespace Bitrix\Seo\WebHook\Payload;

class LeadItem extends Item
{
    protected $data = [
        'leadId' => null,
        'groupId' => null,
        'userId' => null,
        'formId' => null,
        'answers' => [],
        'source' => null,
    ];

    public function addAnswer($key, array $values)
    {
        $answers = $this->getAnswers();
        $answers[$key] = $values;
        return $this->setAnswers($answers);
    }
}