private List<ConfiguredMetric> getMetricDefinitions(ConsumerId consumer) {
        if (metricsConsumers == null) return List.of();

        List<ConfiguredMetric> definitions = metricsConsumers.getMetricDefinitions(consumer);
        return definitions == null ? List.of() : definitions;
    }
Returns the metrics to output for the given service, with updated timestamp
In order to include a metric, it must exist in the given map of metric to consumers.
Each returned metric will contain a collection of consumers that it should be routed to.
metrics-proxy/src/main/java/ai/vespa/metricsproxy/core/VespaMetrics.java