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Your task is to:

1. Add support for change tagging to the two stabilize API actions that are part of the FlaggedRevs extension. (One, called ApiStabilizeGeneral, is used when $wgFlaggedRevsProtection = false, while the other, ApiStabilizeProtect, is used when that setting is true.) This involves adding a new parameter called tags, checking that the user is allowed to apply change tags, and then applying the tags themselves. ApiDelete as of this patch is a good model.
2. Solve the issue in https://phabricator.wikimedia.org/T60498, where the API help output (https://de.wikipedia.org/w/api.php?action=help&modules=review&uselang=en or https://de.wikiquote.org/w/api.php?action=help&modules=review&uselang=en) mentions a parameter that doesn't exist on all wikis.