private static Set<String> metricNames(int statusCode) {
            if (statusCode < 200) return Set.of(MetricDefinitions.RESPONSES_1XX);
            else if (statusCode < 300) return Set.of(MetricDefinitions.RESPONSES_2XX);
            else if (statusCode < 400) return Set.of(MetricDefinitions.RESPONSES_3XX);
            else if (statusCode < 500) return Set.of(MetricDefinitions.RESPONSES_4XX);
            else return Set.of(MetricDefinitions.RESPONSES_5XX);
        }
A {@link RequestLog} implementation that collects statistics like HTTP response types aggregated by category.
Implemented as a {@link RequestLog} instead of {@link org.eclipse.jetty.server.handler.EventsHandler} to ensure
that 400 responses from e.g. invalid request headers are also included.

@author ollivir
@author bjorncs
container-core/src/main/java/com/yahoo/jdisc/http/server/jetty/MetricAggregatingRequestLog.java