anchor.diff:  .Example set-up of a Gauge metric.  No unit is given, so `MetricUnits.NONE` is used, an explicit name is provided
   [source,java]
   ----
  -@Gauge(name = "queueSize")
  +@Gauge(unit = MetricUnits.NONE, name = "queueSize")
   public int getQueueSize() {
     return queue.size;
   }
  
positive.code: .Example of an annotated method
  [source, java]
  ----
  @Gauge
  public long getValue() {
    return value;
  }
  
negative.code: ----
  
  ==== @Gauge
  An annotation for marking a method as a gauge. No default `MetricUnit` is supplied, so the `unit` must always be specified explicitly.
  
  The implementation must support the following annotation target:
  
  