docs: public void setMetricsTrackerFactory(MetricsTrackerFactory metricsTrackerFactory)
     {
        if (metricsTrackerFactory != null) {
           this.metricsTracker = new MetricsTrackerDelegate(metricsTrackerFactory.create(config.getPoolName(), getPoolStats()));
        }
        else {
           this.metricsTracker = new NopMetricsTrackerDelegate();
        }
     }