A DESCRIPTION OF THE PROBLEM :
Please expand the documentation of CompletableFuture and CompletionStage to describe the Memory Model guarantees (e.g. happens-before relationships) these classes and their methods provide. Currently this is not documented for these classes at all, and one can only assume what the guarantees might be.

Compare this to the class Future for which both the package documentation (https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/concurrent/package-summary.html) and the class documentation specify the Memory Model guarantees for the `get()` method.

See also the following Stack Overflow questions about this:
- https://stackoverflow.com/q/61575531
- https://stackoverflow.com/q/34427972