@Override
    public void in(ExportEvent event) {
        if (exportService != null || getModuleDefineHolder().has(ExporterModule.NAME)) {
            if (exportService == null) {
                exportService = getModuleDefineHolder().find(ExporterModule.NAME)
                                                       .provider()
                                                       .getService(MetricValuesExportService.class);
            }
            if (exportService.isEnabled()) {
                exportService.export(event);
            }
        }
    }
A bridge worker. If the {@link ExporterModule} provider declared and provides a implementation of {@link
MetricValuesExportService}, forward the export data to it.
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/worker/ExportMetricsWorker.java