@Override
  public <T> Map<String, T> getGaugeValues(String group, String gauge) {
    return getMetricValues(group, gauge, "Value");
  }
JMX metrics accessor.
It connects to a container JMX url,and get metrics values by querying the MBeans.
samza-core/src/main/java/org/apache/samza/metrics/JmxMetricsAccessor.java