@Override
    public Future<Map<ByteBuffer, ByteBuffer>> get(Collection<ByteBuffer> keys) {
        CompletableFuture<Void> endFuture = new CompletableFuture<>();
        readToEnd(endFuture);
        return endFuture.thenApply(ignored -> {
            Map<ByteBuffer, ByteBuffer> values = new HashMap<>();
            for (ByteBuffer key : keys) {
                ByteBuffer value = data.get(key);
                if (null != value) {
                    values.put(key, value);
                }
            }
            return values;
        });
    }
@Test
    public void testGetFromEmpty() throws Exception {
        testOffsetBackingStore(false);
        assertTrue(offsetBackingStore.get(
            Arrays.asList(ByteBuffer.wrap("empty-key".getBytes(UTF_8)))
        ).get().isEmpty());
    }