code: public void add(String toAdd) {
          if (toAdd.contains("*")) {
              set.clear();
              defaultContains = true;
          } else {
              if (!defaultContains) {
                  set.add(toAdd);
              } else {
                  set.remove(toAdd);
              }
          }
      }
docs: Add some tokens to the list. By default the list is empty. If the list already contains the added tokens or
  everything, this method will have no effect.
  
  @param toAdd
  String token to add to the list. This argument can be:
  <ul>
  <li>A single String token</li>
  <li>* (in this case the list will then act as if it contained any token but you will be able to make
  except some tokens using the remove method)</li>
  </ul>