@Test protected void getTraces_serviceNames_mixedTraceIdLength(TestInfo testInfo)
    throws Exception {
    String testSuffix = testSuffix(testInfo);
    Span clientSpan = newClientSpan(testSuffix);

    // add a trace with the same trace ID truncated to 64 bits, except different service names.
    accept(spanBuilder(testSuffix)
      .traceId(clientSpan.traceId().substring(16))
      .localEndpoint(Endpoint.newBuilder().serviceName(appendSuffix("foo", testSuffix)).build())
      .remoteEndpoint(Endpoint.newBuilder().serviceName(appendSuffix("bar", testSuffix)).build())
      .build());

    getTraces_serviceNames(clientSpan);
  }
This is unlikely and means instrumentation sends empty spans by mistake.
zipkin-tests/src/main/java/zipkin2/storage/ITSpanStore.java