public function setFormat($format)
    {
        if (!in_array($format, self::$supportedFormats)) {
            throw new BuildException(
                sprintf(
                    'Invalid output format "%s", allowed are: %s',
                    $format,
                    implode(', ', self::$supportedFormats)
                )
            );
        }
        $this->format = $format;
    }