@Test protected void consumer_implementsCall_execute(TestInfo testInfo) throws Exception {
    String testSuffix = testSuffix(testInfo);
    Span span = spanBuilder(testSuffix).build();

    Call<Void> call = storage.spanConsumer().accept(List.of(span));

    // Ensure the implementation didn't accidentally do I/O at assembly time.
    assertGetTraceReturnsEmpty(span.traceId());
    call.execute();
    blockWhileInFlight();

    assertGetTraceReturns(span);

    assertThatThrownBy(call::execute)
      .isInstanceOf(IllegalStateException.class);

    // no problem to clone a call
    call.clone().execute();
  }
This is unlikely and means instrumentation sends empty spans by mistake.
zipkin-tests/src/main/java/zipkin2/storage/ITSpanStore.java