We totally missed the docs for that with the 3.0 release, thanks for the heads up.
I've just updated the docs for the Reporter Interface (
https://jasmine.github.io/api/3.0/Reporter.html) and the custom reporter tutorial (
https://jasmine.github.io/tutorials/custom_reporter) for how to make your callbacks async. The short answer is they should work in the same ways that other callbacks (like `it`) do; you should do one of: receive a `done` callback, return a `Promise`, or use the `async` keyword.
Hope this helps. Thanks for using Jasmine!
- Gregg