docs: public static void registerQueueLengthMetrics(MetricGroup group, SingleInputGate gate) {
  		InputGateMetrics metrics = new InputGateMetrics(gate);
  
  		group.gauge("totalQueueLen", metrics.getTotalQueueLenGauge());
  		group.gauge("minQueueLen", metrics.getMinQueueLenGauge());
  		group.gauge("maxQueueLen", metrics.getMaxQueueLenGauge());
  		group.gauge("avgQueueLen", metrics.getAvgQueueLenGauge());
  	}