CheckChatAddParams.php

<?php
 
namespace Bitrix\Im\V2\Controller\Filter;
 
use Bitrix\Im\V2\Chat;
use Bitrix\Main\Engine\ActionFilter\Base;
use Bitrix\Main\Error;
use Bitrix\Main\Event;
use Bitrix\Main\EventResult;
 
class CheckChatAddParams extends Base
{
    public function onBeforeAction(Event $event)
    {
        $arguments = $this->getAction()->getArguments();
        if (!isset($arguments['fields']))
        {
            $this->addError(new Error(
                'Parameter fields is required',
                Chat\ChatError::WRONG_PARAMETER
            ));
            return new EventResult(EventResult::ERROR, null, null, $this);
        }
 
        return null;
    }
}