Hi, As pointed out in this comment https://github.com/apache/kafka/pull/5539#discussion_r212380648 "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.
KIP: https://cwiki.apache.org/confluence/display/KAFKA/KIP-366%3A+Make+FunctionConversions+private Please make your votes. Thanks
