private function listPublication(Feed $feed, User $user = null)
    {
        return [
            'id'            => $feed->getId(),
            'title'         => $feed->getTitle(),
            'subtitle'      => $feed->getSubtitle(),
            'total_entries' => $feed->getCountTotalEntries(),
            'icon'          => $feed->getIconUrl(),
            'public'        => $feed->isPublic(),
            'readonly'      => !$feed->isPublisher($user),
            'deletable'     => $feed->isOwner($user),
            'created_on'    => $feed->getCreatedOn()->format(DATE_ATOM),
            'updated_on'    => $feed->getUpdatedOn()->format(DATE_ATOM),
        ];
    }