A newly opened change stream cursor returns null for `getResumeToken()`. This makes fault tolerance cumbersome and full of corner cases during the period before the cursor acquires its resume token, which can take a long time on a quiescent database. There exists a way to cause a change stream cursor to acquire a resume token immediately, even before it sees its first event, by calling `tryNext`. However, this also causes the cursor to block for the polling period (`maxAwaitTime`), and shortening the polling period has other adverse effects. Fault tolerance and recovery logic would be significantly simpler if successfully opening a change stream cursor also caused it to have a valid resume token. Corner cases in this kind of recovery logic are particularly tricky to test, and particularly costly if the logic fails in production.