class ZMSFileChangeLogStoreCommon {

    public String retrieveTagHeader(Map<String, List<String>> responseHeaders) {

        // our tag value is going to be returned from the server in the
        // response headers as the value to the key "tag"

        List<String> tagData = responseHeaders.get(ATTR_TAG);
        if (tagData == null || tagData.isEmpty()) {
            LOGGER.error("Response headers from ZMS does not include 'ETag/tag' value");
            return null;
        }
        return tagData.get(0);
    }

    public  ZMSFileChangeLogStoreCommon(final String rootDirectory);

}