code: public EtcdResult cad(String key, Map<String, String> params) throws EtcdClientException {
          URI uri = buildUriWithKeyAndParams(key, params);
          HttpDelete httpDelete = new HttpDelete(uri);
  
          return syncExecute(httpDelete, new int[] {200, 412}, 101);
      }
docs: Atomic Compare-and-Delete
  @param key the key
  @param params comparable conditions
  @return operation result
  @throws EtcdClientException