code: static VersionNumber identifyBSDVersion(final String userAgent) {
  		VersionNumber version = VersionNumber.UNKNOWN;
  		final Pattern pattern = Pattern.compile("\\w+bsd\\s?((\\d+)((\\.\\d+)+)?((\\-|_)[\\w\\d\\-]+)?)", Pattern.CASE_INSENSITIVE);
  		final Matcher m = pattern.matcher(userAgent);
  		if (m.find()) {
  			version = parseFirstVersionNumber(m.group(MAJOR_INDEX));
  		}
  		return version;
  	}
docs: This method try to determine the version number of an operating system of a <i>BSD</i> platform more accurately.
  
  @param userAgent
  user agent string
  @return more accurately identified version number or {@code null}