With formatversion=1, boolean response fields are typically returned as the
empty string when true and are absent from the response when false. With
formatversion=2, boolean response fields in JSON and PHP formats are
supposed to be returned as native boolean true when true, and either native
boolean false or absent from the response when false.
Any boolean response fields that use the formatversion=1 semantics with
formatversion=2 should be fixed. Please file tasks in Phabricator if you
encounter such fields.[1] Clients using formatversion=2 should be prepared
for such response fields to be fixed without further warning.
[1]:
https://phabricator.wikimedia.org/maniphest/task/edit/form/1/?tag=MediaWiki…
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Brad Jorsch (Anomie)
Senior Software Engineer
Wikimedia Foundation