public <T> Gauge<T> newGauge(String name, final MetricGroup.ValueFunction<T> valueFunc) {
    return group.newGauge(name, valueFunc);
  }
A base class for metrics. The name of the class that extends the
base class will be used as the metric group name
samza-core/src/main/java/org/apache/samza/metrics/MetricsBase.java