code: public static List<Word> split(Word word){
          String value = GENERIC_TRIE.get(word.getText());
          if(value==null){
              return null;
          }
          List<Word> words = new ArrayList<>();
          for(String val : value.split("\\s+")){
              words.add(new Word(val));
          }
          if(words.isEmpty()){
              return null;
          }
          return words;
      }
docs: 将一个词拆分成几个，返回null表示不能拆分
  @param word
  @return