NoopStatisticsService implements StatisticsService { @Override public void persist(TransmissionRequest transmissionRequest, TransmissionResponse transmissionResponse, Span root) { }  @Override void persist(TransmissionRequest transmissionRequest,
                        TransmissionResponse transmissionResponse, Span root); @Override void persist(InboundMetadata inboundMetadata);  }
@Test public void simple() { statisticsService.persist(null, null, null); statisticsService.persist(null); }