This commit deprecates ListenableFuture in favor of CompletableFuture.
ListenableFuture was introduced in Spring Framework 4.0, when
CompletableFuture was not yet available. Spring now requires JDK 17, so
having our own type no longer seems necessary.
Major changes in this commit include:
- Deprecation of ListenableFuture and related types
(ListenableFutureCallback, SettableListenableFuture, etc.)
- Deprecation of AsyncListenableTaskExecutor in favor of default methods
in AsyncTaskExecutor (submitCompletable).
- AsyncHandlerMethodReturnValueHandler now has toCompletableFuture
instead of toListenableFuture.
- WebSocketClient now has execute methods, which do the same as
doHandshake, but return CompletableFutures (cf. the reactive
WebSocketClient).
All other changes
- add an overloaded method that takes a CompletableFuture parameter
instead of ListenableFuture, and/or
- add a method with a 'Async' suffix that returns a CompletableFuture
instead of a ListenableFuture (connectAsync, sendAsync).
Closes gh-27780
2aa74c9121