Current state: Adopted (2.1.0)
Discussion thread: here
Github PR: here
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
As pointed out in this comment #5539 (comment) "This class was already defaulted to public visibility, and we can't retract it now, without a KIP.", the object FunctionConversions is only of internal use and therefore should be private to the lib only so that we can do changes without going through KIP like this one.
Make this object deprecated and rely on a private version of it.
Compatibility, Deprecation, and Migration Plan
Go though a deprecation.