static SpanBytesDecoder testForUnexpectedFormat(BytesDecoder<Span> decoder, ByteBuffer body) {
    if (decoder == SpanBytesDecoder.JSON_V2) {
      if (contains(body, BINARY_ANNOTATION_FIELD_SUFFIX)) {
        return SpanBytesDecoder.JSON_V1;
      }
    } else if (decoder == SpanBytesDecoder.JSON_V1) {
      if (contains(body, ENDPOINT_FIELD_SUFFIX) || contains(body, TAGS_FIELD)) {
        return SpanBytesDecoder.JSON_V2;
      }
    }
    return null;
  }
Some formats clash on partial data. For example, a v1 and v2 span is identical if only the span
name is sent. This looks for unexpected data format.
zipkin-server/src/main/java/zipkin2/server/internal/ZipkinHttpCollector.java