@Test void traceByServiceSpan_indexesDurationInMillis() {
    Span span = spanWithoutAnnotationsOrTags;

    AggregateCall<?, Void> call = (AggregateCall<?, Void>) consumer.accept(List.of(span));
    assertThat(call.delegate())
      .filteredOn(c -> c instanceof InsertTraceByServiceSpan)
      .extracting("input.duration")
      .containsOnly(span.durationAsLong() / 1000L);
  }
To allow lookups w/o a span name, we index "". "" is used instead of null to avoid creating
tombstones.
zipkin-storage/cassandra/src/test/java/zipkin2/storage/cassandra/CassandraSpanConsumerTest.java