@Override
            public void onNext(final LogData logData) {
                if (log.isDebugEnabled()) {
                    log.debug("received log in streaming");
                }
                HistogramMetrics.Timer timer = histogram.createTimer();
                try {
                    LogData.Builder builder = logData.toBuilder();
                    setServiceName(builder);
                    logAnalyzerService.doAnalysis(builder, null);
                } catch (Exception e) {
                    errorCounter.inc();
                    log.error(e.getMessage(), e);
                } finally {
                    timer.finish();
                }
            }
If this is not the first element of the streaming,
use the previous not-null name as the service name.
oap-server/server-receiver-plugin/skywalking-log-receiver-plugin/src/main/java/org/apache/skywalking/oap/server/receiver/log/provider/handler/grpc/LogReportServiceGrpcHandler.java