code: protected void lookup(String lemma, String posTag, List<String> results) {
      synchronized (this) { // the stemmer is not thread-safe
        List<WordData> wordForms = stemmer.lookup(lemma + "|" + posTag);
        for (WordData wd : wordForms) {
          results.add(wd.getStem().toString());
        }
      }
    }
docs: Lookup the inflected forms of a lemma defined by a part-of-speech tag.
  @param lemma the lemma to be inflected.
  @param posTag the desired part-of-speech tag.
  @param results the list to collect the inflected forms.