public function update($id, array $params)
    {
        $defaults = [
            'id' => $id,
            'subject' => null,
            'notes' => null,
            'private_notes' => false,
            'category_id' => null,
            'priority_id' => null,
            'status_id' => null,
            'tracker_id' => null,
            'assigned_to_id' => null,
            'due_date' => null,
        ];
        $params = $this->cleanParams($params);
        $params = $this->sanitizeParams($defaults, $params);

        $xml = $this->buildXML($params);

        return $this->put('/issues/'.$id.'.xml', $xml->asXML());
    }