code: public List<String> getClasses() {
      	String classAttr = getAttribute("class");
      	return Stream.of((classAttr == null ? "" : classAttr).trim().split("\\s+")).distinct().sorted().collect(Collectors.toList());
      }
docs: Returns the class names present on element.
  The result is a unique set and is in alphabetical order.
  
  @return the class names present on element.