items.entrySet().stream().filter(e -> String.valueOf(e.getKey()).startsWith(prefix)).sorted(comparingByStringifiedKey()).forEach(e -> {
            System.out.printf("   %s=%s\n", e.getKey(), e.getValue());
        });
    }

    private static Comparator<Map.Entry<?, ?>> comparingByStringifiedKey() {
        return Comparator.comparing(entry -> String.valueOf(entry.getKey()));
    }