@Override
  public Map<String, Long> getCounterValues(String group, String counter) {
    return getMetricValues(group, counter, "Count");
  }
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