Previously these would get extracted unlike other private methods even if the class was a standard library or other external class. This could cause inconsistencies because if we also compiled the class from source we could end up deciding different names for the property's setter: setXyz$private when seen from source, and setXyz without a
suffix when seen as an external .class file. Avoiding extracting these functions from the external perspective both restores consistency with other kinds of method and avoids these consistency problems.
