@Override
  public void init(MetricsConfiguration metricsConfig, MetricsSink sink) {
    super.init(metricsConfig, sink);
    configuration = metricsConfig;
    initializeFilterSets();
    LOG.info("Initialized Ambari DB Metrics Source...");
  }
@{link DatabaseMetricsSource} collects database metrics which is generated through Eclipselink PerformanceMonitor,
and publishes to configured Metric Sink.
ambari-server/src/main/java/org/apache/ambari/server/metrics/system/impl/DatabaseMetricsSource.java