public static String concatToAbs(String f, String s) {
public static String concatToAbs(String f, String s) throws SVNException {
    public static String concatToAbs(String f, String s) {        f = f == null || "".equals(f) ? "/" : f;        s = s == null ? "" : s;                if("/".equals(f)){            if(s.startsWith("/")){                return s;            }            return "/" + s;        }        return append(f, s);    }