@Override
    public <U> CompletableFuture<U> handle(BiFunction<? super V, Throwable, ? extends U> fn) {
        return future.handleAsync(new HandleBiFunction<>(fn), defaultExecutor());
    }
@Test
    public void handle() {
        CompletableFuture<Long> nextStage = delegatingFuture.handle((v, t) -> {
            assertEquals(DESERIALIZED_VALUE, v);
            return 1L;
        });
        invocationFuture.complete(response);

        assertTrueEventually(() -> assertTrue(nextStage.isDone()));
        assertEquals(1L, nextStage.join().longValue());
    }