code: public final void addFields(Document document, CellName cellName) {
          String serializedKey = ByteBufferUtils.toString(cellName.toByteBuffer());
          Field field = new StringField(FIELD_NAME, serializedKey, Field.Store.YES);
          document.add(field);
      }
docs: Adds to the specified document the clustering key contained in the specified cell name.
  
  @param document The document where the clustering key is going to be added.
  @param cellName A cell name containing the clustering key to be added.