/**
     * The Merkle hashes of the roots which make up this file collection fingerprint.
     */
    ImmutableMultimap<String, HashCode> getRootHashes();

    boolean wasCreatedWithStrategy(FingerprintingStrategy strategy);

    FileCollectionFingerprint EMPTY = new FileCollectionFingerprint() {
        @Override
        public Map<String, FileSystemLocationFingerprint> getFingerprints() {

        ImmutableMultimap<String, HashCode> rootHashes = SnapshotUtil.getRootHashes(roots);
        Map<String, FileSystemLocationFingerprint> fingerprints;
        if (candidate != null
            && candidate.wasCreatedWithStrategy(strategy)
            && equalRootHashes(candidate.getRootHashes(), rootHashes)
        ) {
            fingerprints = candidate.getFingerprints();
        } else {

        return fingerprints;
    }

    @Override
    public ImmutableMultimap<String, HashCode> getRootHashes() {
        return rootHashes;
    }

    @Override
    public boolean wasCreatedWithStrategy(FingerprintingStrategy strategy) {
        return strategy.getConfigurationHash().equals(strategyConfigurationHash);
    }

    public HashCode getStrategyConfigurationHash() {

    }

    @Override
    public ImmutableMultimap<String, HashCode> getRootHashes() {
        return ImmutableMultimap.of();
    }

    @Override
    public boolean wasCreatedWithStrategy(FingerprintingStrategy strategy) {
        return false;
    }

    @Override
    public String getStrategyIdentifier() {
        return identifier;
    }

    @Override