HTTPS required for ACUR?

[ericlaw1979]

https://microsoftedge.github.io/WebAppsDocs/en-US/win10/CreateHWA.htm Step 5 shows using HTTP URIs when setting ACUR rules.

However, https://msdn.microsoft.com/en-us/library/windows/desktop/dn457654(v=vs.85).aspx implies that only HTTPS URIs are acceptable.

Which is it?