VersionInfo info = infos.get(key);
        if (info == null) {
            info = new VersionInfo(timestamp, version, repository);
            infos.put(key, info);
        } else if (info.isOutdated(timestamp)) {
            info.version = version;
            info.repository = repository;
            info.timestamp = timestamp;
        }
    }

        if (input == null) {
            return StringUtil.EMPTY;
        }
        return input;
    }

    public boolean isUpdated() {
        return newInput != null;
    }

    public boolean isDeleted() {
        return isUpdated() && newInput.length() == 0;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        final int result = 1;

    public String getInput() {
        return input;
    }

    public String getOutput() {
        return output;
    }

    public boolean isUpdated() {
        return newInput != null && newOutput != null;
    }

    public boolean isDeleted() {
        return isUpdated() && StringUtil.isBlank(newInput);
    }

    @Override
    public int hashCode() {
        return Objects.hash(input, output);
    }

        }
        return String.join("\n", inputs);
    }

    public String getOutput() {
        return output;
    }

    public boolean isUpdated() {
        return newInputs != null && newOutput != null;
    }

    public boolean isDeleted() {
        return isUpdated() && newInputs.length == 0;
    }

    public void sort() {
        if (inputs != null) {
            Arrays.sort(inputs);
        }

        if (input == null) {
            return StringUtil.EMPTY;
        }
        return input;
    }

    public boolean isUpdated() {
        return newInput != null;
    }

    public boolean isDeleted() {
        return isUpdated() && newInput.length() == 0;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        final int result = 1;

        if (outputs == null) {
            return StringUtil.EMPTY;
        }
        return String.join("\n", outputs);
    }

    public boolean isUpdated() {
        return newInputs != null && newOutputs != null;
    }

    public boolean isDeleted() {
        return isUpdated() && newInputs.length == 0;
    }

    @Override
    public int hashCode() {

    public String getReading() {
        return reading;
    }

    public String getPos() {
        return pos;
    }

    public boolean isUpdated() {
        return newToken != null;
    }

    public boolean isDeleted() {
        return isUpdated() && newToken.length() == 0;
    }

    @Override
    public int hashCode() {
        return Objects.hash(pos, reading, segmentation, token);
    }

            item = newItem;
        }

        public CharMappingItem write(final CharMappingItem oldItem) {
            try {
                if (item == null || item.getId() != oldItem.getId() || !item.isUpdated()) {
                    writer.write(oldItem.toLineString());
                    writer.write(Constants.LINE_SEPARATOR);
                    return oldItem;
                }

            }
            item = newItem;
        }

        public KuromojiItem write(final KuromojiItem oldItem) {
            try {
                if (item == null || item.getId() != oldItem.getId() || !item.isUpdated()) {
                    writer.write(oldItem.toLineString());
                    writer.write(Constants.LINE_SEPARATOR);
                    return oldItem;
                }

            }
            item = newItem;
        }

        public SynonymItem write(final SynonymItem oldItem) {
            try {
                if (item == null || item.getId() != oldItem.getId() || !item.isUpdated()) {
                    writer.write(oldItem.toLineString());
                    writer.write(Constants.LINE_SEPARATOR);
                    return oldItem;
                }