QFutureInterface public interface

In standard C++ library since C++11 we've got a std::promise class that allows to acquire computation results (or exception) asynchronously by producing std::future which is bounded to it.
There is such std::promise-like class in Qt named QFutureInterface that serves for same purposes AFAIK. But it's not documented and so there are no assurances of keeping QFutureInterface interface unchanged in each Qt version.
Could you provide public QFutureInterface documentation for user purposes, please.