code: public static <T> ListenableFuture<T> toListenableFuture(CompletableFuture<T> completableFuture) {
          return SpringFutureUtils.createListenableFuture(Java8FutureUtils.createValueSourceFuture(completableFuture));
      }
docs: Converts {@link java.util.concurrent.CompletableFuture} to {@link org.springframework.util.concurrent.ListenableFuture}.