We've procrastinated on making this API public for about ten years now,
and in the meanwhile there has been exactly one disruptive change to
the API. As in, it might've just as well been public all along.
There will always be more things to improve wrt any API, but we're not
going to hold this hostage to one more thing or another anymore. Some
of them we'd like to do before this goes to a stable release (ie 4.20)
but doing this now to kinda enforce this actually happens this time
around, through come hell or high water.
Fixes: #1536
959b4e4750