UserRepository::getParticipants

public function getParticipants(TaskObject $task, array $optional = []): array
{
	return array_unique(
		array_merge(
			[$task->getCreatedBy(), $task->getResponsibleId()],
			$task->getAccompliceMembersIds(),
			$task->getAuditorMembersIds(),
			(array)($optional['additional_recepients'] ?? [])
		)
	);
}