Event::getEntitiesByType

static function getEntitiesByType(array $recipientList): ?array
{
	$result = [
		'users' => [],
		'channels' => [],
		'count' => 0,
	];
	foreach ($recipientList as $entity)
	{
		if ($entity instanceof BitrixPullModelChannel)
		{
			$result['channels'][] = $entity->getPrivateId();
			$result['count']++;
		}
		else if (self::isChannelEntity($entity))
		{
			$result['channels'][] = $entity;
			$result['count']++;
		}
		else
		{
			$result['users'][] = intval($entity);
			$result['count']++;
		}
	}

	return $result['count'] > 0 ? $result : null;
}