code: private static void examineOperatingSystem(final UserAgent.Builder builder, final Data data) {
  		if (net.sf.uadetector.OperatingSystem.EMPTY.equals(builder.getOperatingSystem())) {
  			for (final Entry<OperatingSystemPattern, OperatingSystem> entry : data.getPatternToOperatingSystemMap().entrySet()) {
  				final Matcher matcher = entry.getKey().getPattern().matcher(builder.getUserAgentString());
  				if (matcher.find()) {
  					entry.getValue().copyTo(builder);
  					break;
  				}
  			}
  		}
  	}
docs: Examines the operating system of the user agent string, if not available.
  
  @param userAgent
  String of an user agent
  @param builder
  Builder for an user agent information