What are the detailed specifications about "Added support for automatic HTTPS upgrades." ?

In safari-15-beta-release-notes (https://developer.apple.com/documentation/Safari-Release-Notes/safari-15-beta-release-notes),

Added support for automatic HTTPS upgrades.

is written as one of new features regarding security & privacy.

I want to know more detail about this, but there is no article in webkit blog about this. If you know about this, please tell me the detailed specifications about "Added support for automatic HTTPS upgrades."

If you know about this, please tell me the detailed specifications about "Added support for automatic HTTPS upgrades."

I inquired about this and it is for connection upgrades to wss for the WebSocket API. However, this is for only specific domains. I do not have the list of domains this applies to, but for more information I would open an enhancement request to get this documented.

Matt Eaton
DTS Engineering, CoreOS
meaton3@apple.com
What are the detailed specifications about "Added support for automatic HTTPS upgrades." ?
 
 
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