The commit message for https://gerrit.wikimedia.org/r/#/c/180588/ says
For consistency everything is now in the form of: post-revision-id, topic-revision-id, header-revision-id, etc.
But I edited a Flow board header and the API response contained flow.edit-header.committed.header.revision-id. The key isn't prefixed with "header-". It's not ambiguous as it's in a different key in the response than e.g. flow.newtopic.committed; which is the intended design? Flow/Architecture/API documents the API.