@Override public int listSizeInBytes(List<byte[]> values) {
      int sizeInBytes = 2; // brackets
      for (int i = 0, length = values.size(); i < length; ) {
        sizeInBytes += values.get(i++).length;
        if (i < length) sizeInBytes++;
      }
      return sizeInBytes;
    }
Encoding overhead is brackets and a comma for each span over 1
zipkin/src/main/java/zipkin2/codec/Encoding.java