That's why code reviews exist, it's good process to make code reviews mandatory.
replyIt's too much of a stretch to call null an escape hatch, or to pretend that code reviews will somehow strip it out.
replyThe OpenJDK HashMap returns null from get(), put() and remove(), among others. Is this just because it hasn't been reviewed enough yet?
> pretend that code reviews will somehow strip it out.
replyCode reviews 'somehow' strip out poorly thought out new uses of escape hatches.
For your example, it would be an use of get, put or remove without checking the result.