code: @Nonnull
  	public DataBuilder appendOperatingSystemPattern(@Nonnull final OperatingSystemPattern pattern) {
  		Check.notNull(pattern, "pattern");
  
  		if (!operatingSystemPatterns.containsKey(pattern.getId())) {
  			operatingSystemPatterns.put(pattern.getId(), new TreeSet<OperatingSystemPattern>(OS_PATTERN_COMPARATOR));
  		}
  
  		operatingSystemPatterns.get(pattern.getId()).add(pattern);
  		return this;
  	}
docs: Appends an operating system pattern to the map of pattern sorted by ID.
  
  @param pattern
  a pattern for a browser
  @throws net.sf.qualitycheck.exception.IllegalNullArgumentException
  if the pattern is {@code null}
  @return itself