public static Function<? super HttpService, MetricCollectingService> newDecorator(
            MeterIdPrefixFunction meterIdPrefixFunction) {

        requireNonNull(meterIdPrefixFunction, "meterIdPrefixFunction");
        return builder(meterIdPrefixFunction).newDecorator();
    }
Returns a new {@link HttpService} decorator that tracks request stats using {@link MeterRegistry}.
core/src/main/java/com/linecorp/armeria/server/metric/MetricCollectingService.java