@Deprecated
    public AbstractMetricCollectingBuilder successFunction(
            BiPredicate<? super RequestContext, ? super RequestLog> successFunction) {
        this.successFunction = requireNonNull(successFunction, "successFunction");
        return this;
    }
Defines a custom {@link BiPredicate} to allow custom definition of successful responses.
In other words, specify which responses should increment {@code metrics.success()}
and which - {@code metrics.failure()}.

<p>Example:
<pre>{@code
    MetricCollectingService
        .builder(MeterIdPrefixFunction.ofDefault("hello"))
        .successFunction((context, log) -> {
            final int statusCode = log.responseHeaders().status().code();
            return (statusCode >= 200 && statusCode < 400) || statusCode == 404;
        })
        .newDecorator();
}</pre>

@deprecated Use {@link ClientBuilder#successFunction(SuccessFunction)} or
                {@link ServerBuilder#successFunction(SuccessFunction)}.
core/src/main/java/com/linecorp/armeria/common/metric/AbstractMetricCollectingBuilder.java