code: public String[] getFeatNames() {
          String[] namesArray = new String[nameIndexMap.size()];
  
          for (Map.Entry<String, Integer> entry : nameIndexMap.entrySet()) {
              namesArray[entry.getValue()] = entry.getKey();
          }
  
          return namesArray;
      }
docs: This method should only be used for print or debug purpose.
  
  @return Array of feat names. Index corresponding to feat vector's Index.