@Test void span_noLocalServiceName_PROTO3() {
    span = span.toBuilder().localEndpoint(FRONTEND.toBuilder().serviceName(null).build()).build();

    assertThat(SpanBytesEncoder.PROTO3.encode(span)).hasSize(172);
  }
the following skeletal span is used in dependency linking
zipkin/src/test/java/zipkin2/codec/SpanBytesEncoderTest.java