this.hashCodeSerializer = new HashCodeSerializer();
    }

    @Override
    public FileCollectionFingerprint read(Decoder decoder) throws IOException {
        Map<String, FileSystemLocationFingerprint> fingerprints = fingerprintMapSerializer.read(decoder);
        if (fingerprints.isEmpty()) {
            return FileCollectionFingerprint.EMPTY;
        }
        ImmutableMultimap<String, HashCode> rootHashes = readRootHashes(decoder);