code: public static MutableSet<String> tokensToSet(String string, String separator)
      {
          MutableSet<String> set = UnifiedSet.newSet();
          for (StringTokenizer stringTokenizer = new StringTokenizer(string, separator); stringTokenizer.hasMoreTokens(); )
          {
              String token = stringTokenizer.nextToken();
              set.add(token);
          }
          return set;
      }
docs: Converts a string of tokens to a {@link MutableSet}.