Task::updateViewDate

private function updateViewDate(array $fields)
{
	$taskData = $this->getFullTaskData();
	if (!$taskData)
	{
		return;
	}

	$newParticipants = $this->getParticipants($taskData);
	$oldParticipants = $this->getParticipants($this->sourceTaskData);
	$addedParticipants = array_unique(array_diff($newParticipants, $oldParticipants));

	if (
		!empty($addedParticipants)
		&& $viewedDate = BitrixTasksCommentsTask::getLastCommentTime($this->taskId)
	)
	{
		foreach ($addedParticipants as $userId)
		{
			ViewedTable::set($this->taskId, $userId, $viewedDate);
		}
	}
}