code: @Override
      public byte[] getValue() {
          StringBuilder sb = new StringBuilder(64);
          sb.append(component).append(MetricUtils.AT).append(taskId).append(MetricUtils.AT)
                  .append(streamId).append(MetricUtils.AT).append(metricType).append(MetricUtils.AT)
                  .append(host).append(MetricUtils.AT).append(port).append(MetricUtils.AT)
                  .append(metricGroup).append(MetricUtils.AT).append(metricName);
          return sb.toString().getBytes();
      }
docs: value: component + taskId + streamId + metricType + host + port + metricGroup + metricName