@Test void traceIdFromLong_128() {
    assertThat(base.toBuilder().traceId(1234L, 5678L).build().traceId())
      .isEqualTo("00000000000004d2000000000000162e");
  }
Test serializable as used in spark jobs. Careful to include all non-standard fields
zipkin/src/test/java/zipkin2/SpanTest.java