@Override
  public int hashCode() {
    return new HashCodeBuilder().append(metricsName).append(metricsDescription)
      .append(metricsContext).append(metricsJmxContext).toHashCode();
  }
Returns whether or not this MetricRegistry is for an existing BaseSource
@return true if this MetricRegistry is for an existing BaseSource.
hbase-metrics-api/src/main/java/org/apache/hadoop/hbase/metrics/MetricRegistryInfo.java