It's suggested that the person that prepares Druid Release Notes (I think it's Jon usually) goes through all PRs labelled "Area - Metrics/Event Emitting" ( https://github.com/apache/incubator-druid/pulls?q=is%3Apr+sort%3Aupdated-desc+label%3A%22Area+-+Metrics%2FEvent+Emitting%22+is%3Aclosed+milestone%3A0.13.0) along with "Release Notes", to present this information in the release notes.
BTW I wonder is the a document in the repository or elsewhere that describes the release process?
