code: private static String getMasterMetricName(String name) {
      String result = CACHED_METRICS.get(name);
      if (result != null) {
        return result;
      }
      return CACHED_METRICS.computeIfAbsent(name, n -> InstanceType.MASTER.toString() + "." + name);
    }
docs: Builds metric registry names for master instance. The pattern is instance.metricName.
  
  @param name the metric name
  @return the metric registry name