public function isOnDraft()
    {
        $id = $this->owner->ID ?: $this->owner->OldID;
        if (!$id) {
            return false;
        }
        if (!$this->hasStages()) {
            return true;
        }

        $draftVersion = static::get_versionnumber_by_stage($this->owner, Versioned::DRAFT, $id);
        return (bool)$draftVersion;
    }