public void appendMetrics(ZabbixConfig config) {
            // Append metrics to converters
            metricConverts.add(new MetricConvert(config, meterSystem));

            // Append labels and add to item keys
            if (CollectionUtils.isNotEmpty(config.getEntities().getLabels())) {
                labels.addAll(config.getEntities().getLabels());

                config.getEntities().getLabels().stream().filter(l -> StringUtils.isNotBlank(l.getFromItem()))
                    .forEach(l -> enabledKeys.add(l.getFromItem()));
            }

            // Append all metric keys
            enabledKeys.addAll(config.getRequiredZabbixItemKeys());
        }
The group of instances according to hostPatterns defined in Zabbix rule file
oap-server/server-receiver-plugin/skywalking-zabbix-receiver-plugin/src/main/java/org/apache/skywalking/oap/server/receiver/zabbix/provider/ZabbixMetrics.java