The @Asynchronous policy

Making an operation asynchronous is as simple as the following:

@Asynchronous
public Future<Connection> service() throws InterruptedException {
  Connection conn = new Connection() {
    {
      Thread.sleep(1000);
    }
 
    @Override
    public String getData() {
      return "service DATA";
    }
 };
 return CompletableFuture.completedFuture(conn);
}

The only constraint is to have the @Asynchronous method return Future or CompletionStage; otherwise, the implementation should throw an exception.