@Test void decoderForListMessage_json_v2_partial_tag() {
    Span span = Span.newBuilder().traceId("a").id("b").putTag("foo", "bar").build();

    byte[] message = SpanBytesEncoder.JSON_V2.encodeList(List.of(span));
    assertThat(SpanBytesDecoderDetector.decoderForListMessage(message))
        .isEqualTo(SpanBytesDecoder.JSON_V2);
  }
Single-element reads were for legacy non-list encoding. Don't add new code that does this
zipkin/src/test/java/zipkin2/SpanBytesDecoderDetectorTest.java