public SamzaHistogram newHistogram(String name, List<Double> percentiles) {
    return new SamzaHistogram(registry, groupName, (prefix + name).toLowerCase(), percentiles);
  }
@param name - Name of the histogram metric
@param percentiles - percentiles you want to record for this metric, such as P50, P90, P99
@return Return a SamzaHistogram to record the percentiles of a specific metric.
samza-core/src/main/java/org/apache/samza/metrics/MetricGroup.java