CURLINFO_PROXYAUTH_AVAIL(3) on macOS
The text 68c7aac494f4, as macOS 10.14.6, macOS 10.14.5, macOS 10.14.4, macOS 10.14.3, macOS 10.14.2, macOS 10.14.1, macOS 10.14, macOS 10.13.6, macOS 10.13.5, macOS 10.13.4, macOS 10.13.3, macOS 10.13.2, macOS 10.13.1, macOS 10.13, macOS 10.12.6 shipped it.
get available HTTP proxy authentication methods