public static ReservedMetadataIdMetrics getReservedMetadataIdMetrics(MetricRegistry metricRegistry) {
    synchronized (ReservedMetadataIdMetrics.class) {
      if (!METRIC_MAP.containsKey(metricRegistry)) {
        METRIC_MAP.put(metricRegistry, new ReservedMetadataIdMetrics(metricRegistry));
      }
      return METRIC_MAP.get(metricRegistry);
    }
  }
Return {@link ReservedMetadataIdMetrics} associated with the specified {@link MetricRegistry} object. If no
{@link ReservedMetadataIdMetrics} is associated with the specified {@link MetricRegistry} object, then create one
and return the created object.
@param metricRegistry {@link MetricRegistry} object.
@return ReservedMetadataIdMetrics object.
ambry-api/src/main/java/com/github/ambry/frontend/ReservedMetadataIdMetrics.java