@Override public Call<Void> accept(List<Span> spans) {
      Call<Void> result = new ThrottledCall(
        delegate.accept(spans), executor, limiter, limiterMetrics, isOverCapacity);

      return tracer != null ? new TracedCall<>(tracer, result, "throttled-accept-spans") : result;
    }
See {@link ThrottledCall#STORAGE_THROTTLE_MAX_CONCURRENCY} if unfamiliar with clearing trace on
exceptions only thrown from one spot.
zipkin-server/src/main/java/zipkin2/server/internal/throttle/ThrottledStorageComponent.java