}
            }
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }
    }

    @Override
    public Optional<String> getString(URI relativeSource, Charset charset) {
        requireNonNull(charset, "charset is null");
        Optional<byte[]> data = getBytes(relativeSource);
        return data.map(bytes -> new String(bytes, charset));
    }