Hi. Thank you for paying attention to my (possibly silly) questions.

I'm using HashMap::entry_ref() and EntryRef::insert() APIs to try to reduce some clone overhead in my project. I found that the trait bound for EntryRef::insert() is &'b Q: Into<K>, rather than mostly used Q: ToOwned<Owned = K>. The &'b Q: Into<K> is a bit inconvenient to expose to the user since the primitives such as u64 hasn't implemented &u64: Into<u64>.

May I ask why this trait bound is used here? Thank you very much. 🙏