Unfortunately, most of the usage of `null_byte` can't replaced with such a function, without introducing performance overhead in WindowsPath. This function would force any `BytesContainer` to become `&[u8]`, which throws away the benefit WindowsPath gets from being able to treat it as `&str`. Basically only `set_filestem()`, `set_extension()`, and `add_extension()` would be able to use it, and I think that having two different ways of triggering `null_byte` is worse than what we have now.