Some servers don't return charset in the Content-Type HTTP header response.

Current implementation defaults to ISO_8859_1 in the absence of charset.

ISO_8859_1 does not encode unicode characters correctly.

https://www.iana.org/assignments/media-types/text/csv and https://lists.w3.org/Archives/Public/public-csv-wg/2014Oct/0114.html
indicate that in the absence of charset UTF-8 should be the assumed default.

Environment details

1. General
2. OS type and version: All
3. Java version: 11
4. google-http-client version(s): latest

External references such as API reference guides

https://www.iana.org/assignments/media-types/text/csv
https://lists.w3.org/Archives/Public/public-csv-wg/2014Oct/0114.html