void bind(AbstractLimiter limiter) {
    // This value should parallel (zipkin_storage.throttle.queue_size + zipkin_storage.throttle.concurrency)
    // It is tracked to make sure it doesn't perpetually increase.  If it does then we're not resolving LimitListeners.
    Gauge.builder("zipkin_storage.throttle.in_flight_requests", limiter::getInflight)
      .description("number of requests the limiter thinks are active")
      .register(registryInstance);
  }
Follows the same naming convention as {@link MicrometerCollectorMetrics}
zipkin-server/src/main/java/zipkin2/server/internal/throttle/MicrometerThrottleMetrics.java