code: public void startMetricReportingWithFileSuffix(State state, String metricsFileSuffix) {
      Properties metricsReportingProps = new Properties();
      metricsReportingProps.putAll(state.getProperties());
  
      String oldMetricsFileSuffix =
          state.getProp(ConfigurationKeys.METRICS_FILE_SUFFIX, ConfigurationKeys.DEFAULT_METRICS_FILE_SUFFIX);
      if (Strings.isNullOrEmpty(oldMetricsFileSuffix)) {
        oldMetricsFileSuffix = metricsFileSuffix;
      } else {
        oldMetricsFileSuffix += "." + metricsFileSuffix;
      }
      metricsReportingProps.setProperty(ConfigurationKeys.METRICS_FILE_SUFFIX, oldMetricsFileSuffix);
      startMetricReporting(metricsReportingProps);
    }
docs: Starts metric reporting and appends the given metrics file suffix to the current value of
  {@link ConfigurationKeys#METRICS_FILE_SUFFIX}.