protected static void addObjectToBuilders(List<MetricsPacket.Builder> builders, JsonNode object)  {
        MetricsPacket.Builder builder = new MetricsPacket.Builder(ServiceId.toServiceId(object.get("application").textValue()));
        builder.timestamp(Instant.ofEpochSecond(object.get("timestamp").longValue()));
        if (object.has("metrics")) {
            JsonNode metrics = object.get("metrics");
            Iterator<?> keys = metrics.fieldNames();
            while(keys.hasNext()) {
                String key = (String) keys.next();
                builder.putMetric(MetricId.toMetricId(key), metrics.get(key).asLong());
            }
        }
        if (object.has("dimensions")) {
            JsonNode dimensions = object.get("dimensions");
            Iterator<?> keys = dimensions.fieldNames();
            while(keys.hasNext()) {
                String key = (String) keys.next();
                builder.putDimension(DimensionId.toDimensionId(key), dimensions.get(key).asText());
            }
        }
        builder.addConsumers(Set.of(ConsumerId.toConsumerId("Vespa")));
        builders.add(builder);
    }
Fetches miscellaneous system metrics for node, including
 - Current coredump processing
 - Health of Vespa services
 - Host life

@author olaa
metrics-proxy/src/main/java/ai/vespa/metricsproxy/node/NodeMetricGatherer.java