protected function buildChunkData($part, $chunk_data)
    {
        $data = [];
        $this->appendData($data, 'apikey',            $part['api_key']);
        $this->appendData($data, 'uri',               $part['uri']);
        $this->appendData($data, 'region',            $part['region']);
        $this->appendData($data, 'upload_id',         $part['upload_id']);

        $this->appendData($data, 'part',              $part['part_num']);
        $this->appendData($data, 'store_location',    $part['location']);
        $this->appendData($data, 'md5',               $chunk_data['md5']);
        $this->appendData($data, 'size',              $chunk_data['size']);

        if ($this->intelligent) {
            $this->appendData($data, 'multipart', true);
            $this->appendData($data, 'offset', $chunk_data['offset']);
        }

        $this->appendSecurity($data);

        array_push($data, [
            'name'      => 'files',
            'contents'  => '',
            'filename'  => $part['filename']]);

        return $data;
    }