public static void testPubKeyCreateNeg() throws AssertFailException{
       byte[] sec = BaseEncoding.base16().lowerCase().decode("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF".toLowerCase());

       byte[] resultArr = NativeSecp256k1.computePubkey( sec);
       String pubkeyString = javax.xml.bind.DatatypeConverter.printHexBinary(resultArr);