code: public Set<String> getKeyList() throws IOException {
      if (dataCollector.getCollectorType()
          .equals(DataCollector.COLLECTOR_TYPE_LIST)) {
        return dataCollector.getResult().getComparatorList().keySet();
      } else {
        throw new IOException(
            "only allowed for " + DataCollector.COLLECTOR_TYPE_LIST);
      }
    }
docs: Gets the key list.
  
  @return the key list
  @throws IOException Signals that an I/O exception has occurred.