7087 Release Notes mention:
Settings|Editor|'Optimise imports on the fly' and 'Add unambiguous imports'
moved into Settings|Code style|Imports to be able to employ them at project level or
I've noticed that while doing so - the old settings were ignored.
I always have both options checked but now after upgrading and later scratching my head why IDEA doesn't add unambiguous by itself - I saw those checkboxes were unchecked in the new settings panel.