autodata (string): The name of automatic data source, if this goal has one. Will be null for manual goals.

[krugerk]

listed here
http://api.beeminder.com/#goal

Bug:
documentation claims this is null for manual goals

but it appears to be empty string (and not nil) for manually sourced goals after removing healthkit

[krugerk]

As is, it needs to be null for some assumptions to catch as expected. However the API call to unset it actually sets it to an empty string instead.

[krugerk]

It seems the iOS client app is responsible for setting and removing the value and it was not unsetting it correctly.
Fixed with beeminder/BeeSwift#437.