public static Function<? super HttpClient, MetricCollectingClient> newDecorator(
            MeterIdPrefixFunction meterIdPrefixFunction) {
        requireNonNull(meterIdPrefixFunction, "meterIdPrefixFunction");
        return builder(meterIdPrefixFunction).newDecorator();
    }
Returns an {@link HttpClient} decorator that tracks request stats using {@link MeterRegistry}.
core/src/main/java/com/linecorp/armeria/client/metric/MetricCollectingClient.java