Closed
Description
http.Server.RegisterOnShutdown was introduced in 1.9 cycle, but it's not mentioned in the release notes, so it's easy to miss, even if it's useful to you.
Documentation for http.Server.Shutdown (that was introduced in 1.8) states:
Shutdown does not attempt to close nor wait for hijacked connections such as WebSockets. The caller of Shutdown should separately notify such long-lived connections of shutdown and wait for them to close, if desired.
IMO this is a good place to mention the new RegisterOnShutdown method to increase awareness of its existence.