code: @Override
      public byte[] getValue() {
          StringBuilder sb = new StringBuilder(32);
          if (start != null) {
              sb.append(KVSerializable.START);
          } else {
              sb.append(KVSerializable.END);
          }
          sb.append(MetricUtils.AT).append(host).append(MetricUtils.AT).append(port);
          return sb.toString().getBytes();
      }
docs: value: type + host + port
  type: S/E (start/end)