@Test public void nextSpan_shouldnt_tag_binary_key() {

  ConsumerRecord<byte[], String> record =
    new ConsumerRecord<>(TEST_TOPIC, 0, 1, new byte[1], TEST_VALUE);
  kafkaTracing.nextSpan(record).start().finish();
  assertThat(spans.get(0).tags())
    .containsOnly(entry("kafka.topic", TEST_TOPIC));
}