@Override int sizeOfValue(Endpoint value) {
      int result = 0;
      result += SERVICE_NAME.sizeInBytes(value.serviceName());
      if (value.ipv4Bytes() != null) result += 6; // tag + size of 4 + 4 bytes
      if (value.ipv6Bytes() != null) result += 18; // tag + size of 16 + 16 bytes
      result += PORT.sizeInBytes(value.portAsInt());
      return result;
    }
This is the only field in the ListOfSpans type
zipkin/src/main/java/zipkin2/internal/Proto3ZipkinFields.java