if (!isCanonical(f)) { SVNErrorMessage err = SVNErrorMessage.create(SVNErrorCode.FS_PATH_SYNTAX, "path component ''{0}'' is not canonical", f); SVNErrorManager.error(err); }  if (!isCanonical(s)) { SVNErrorMessage err = SVNErrorMessage.create(SVNErrorCode.FS_PATH_SYNTAX, "path component ''{0}'' is not canonical", s); SVNErrorManager.error(err); }
    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);    }