code: protected void configureStopWords (String stopWords)
      {
          List<String> patterns = Lists.newArrayList();
          for (StringTokenizer st = new StringTokenizer(stopWords); st.hasMoreTokens(); ) {
              patterns.add(getStopWordRegexp(st.nextToken()));
          }
          String pattern = patterns.isEmpty()
              ? ".\\A" // matches nothing
              : "(" + Joiner.on('|').join(patterns) + ")";
          setStopPattern(pattern);
      }
docs: Configure the words that will stop.