Can NSXPCInterface work with non-void return type?

Can NSXPCInterface work with non-void return type?

The official document says, "All messages must be 'void' return type." (Reference)

However, in the file provider sample code of wwdc21, it uses it with non-void return type. (Reference)

I wondered whether it can or can not be used with non-void return type? Is the answer changed after swift support for async/await?