private Metric.Context createContext(Metrics metrics, Map<String, String> dimensions) {
        if (metrics == null) return null;

        return metrics.getMetric().createContext(dimensions);
    }
Increment the number of requests where we were unable to map host to a {@link RequestHandler}.
configserver/src/main/java/com/yahoo/vespa/config/server/monitoring/MetricUpdater.java