@Test void falseOnEmpty_inputSpans_JSON_V2() {
    assertThat(SpanBytesDecoder.JSON_V2.decodeList(new byte[0], new ArrayList<>()))
      .isFalse();
  }
This isn't a test of what we "should" accept as a span, rather that characters that trip-up
json don't fail in codec.
zipkin/src/test/java/zipkin2/codec/SpanBytesDecoderTest.java