@Override
    public String toString() {
        return "NumberedDirProvider{" +
               "parentDir=" + parentDir +
               ", sequence=" + sequence +
               '}';
    }
Extract the number represented by the supplied `0` padded string.

@param string A directory name.
@return The long part of the string if found, else empty.
stroom-proxy/stroom-proxy-app/src/main/java/stroom/proxy/app/handler/NumberedDirProvider.java