code: private static void gauge(String className, String name, long measurement, String... additionalTags) {
  		getGauge(className, name, additionalTags).getAndSet(measurement);
  	}
docs: Set a gauge is a handle to get the current value. Typical examples for
  gauges would be the size of a queue or number of threads in the running
  state. Since gauges are sampled, there is no information about what might
  have occurred between samples.
  
  @param className
  @param name
  @param measurement
  @param additionalTags