@Override
    public Double getValue() {
      /*
       * We cannot updateGaugeValues if the histogram gauges are being instantiated
       * and getValue is called in this context.
       */
      if (gauges == null) {
        return 0.0;
      }

      updateGaugeValues(percentile);
      return super.getValue();
    }
We update the percentile gauge values when value is being polled.
This is needed for reporters which do not implement MetricsReporter
and do not have MetricsReporter to update the values.
samza-api/src/main/java/org/apache/samza/metrics/SamzaHistogram.java