Board manager contributed JSON doesn't work in Japan

A handful of customers, all in Japan, are reporting that when they put in the adafruit contributed board manager url, they get an error in the IDE

> Skipping contributed index file C:\Users\ccchen\AppData\Local\Arduino15\package_adafruit_index.json, parsing error occured:
> com.fasterxml.jackson.core.JsonParseException: Illegal character ((CTRL-CHAR, code 31)): only regular white space (\r, \n, \t) is allowed between tokens
> at [Source: java.io.FileInputStream@199fc78; line: 1, column: 2]

if they use http it works, https does not. Only happens if they are using the IDE in Japan - VPNing to US works. accessing the json file in a webbrowswer works.

details at : https://forums.adafruit.com/viewtopic.php?f=25&t=123887

No source files, tests, or entry points are identified in the issue. Reproduce the contributed board manager download in the IDE from Japan over HTTPS, compare it with HTTP and a US VPN, and trace where the downloaded JSON reaches the parser. Done means the HTTPS URL works in the reported Japan scenario without the parsing error.

Written by the indexing model from the issue text.