Java X25519 shared secret is not correct when using testing vectors from RFC7748

When using RFC7748 test vectors for elliptic curve diffie hellman in java, I cannot get expected shared secret key. I am able to do so in other languages. I am using openjdk 11 with default Sun security provider. I found official tests which use these test vectors. But I cannot get expected result even if I copy-paste and run them. For instance, here is test that uses these same vectors which will fail if I copy-paste and run locally. It uses some utility functions which are from here, which I also copied. I know I must be doing something wrong but I cannot figure out what exactly. Here is my code:

public class main {
    public static BigInteger hexStringToBigInteger(boolean clearHighBit, String str) {
        BigInteger result = BigInteger.ZERO;
        for (int i = 0; i < str.length() / 2; i++) {
            int curVal = Character.digit(str.charAt(2 * i), 16);
            curVal <<= 4;
            curVal += Character.digit(str.charAt(2 * i + 1), 16);
            if (clearHighBit && i == str.length() / 2 - 1) {
                curVal &= 0x7F;
                result = result.add(BigInteger.valueOf(curVal).shiftLeft(8 * i));
            }
        }
        return result;
    }

    public static byte[] hexStringToByteArray(String str) {
        byte[] result = new byte[str.length() / 2];
        for (int i = 0; i < result.length; i++) {
            result[i] = (byte) Character.digit(str.charAt(2 * i), 16);
            result[i] <<= 4;
            result[i] += Character.digit(str.charAt(2 * i + 1), 16);
        }
        return result;
    }

    public static String byteArrayToHexString(byte[] arr) {
        StringBuilder result = new StringBuilder();
        for (byte curVal : arr) {
            result.append(Character.forDigit(curVal >> 4 & 0xF, 16));
            result.append(Character.forDigit(curVal & 0xF, 16));
        }
        return result.toString();
    }

    private static void runDiffieHellmanTest(String curveName, String a_pri,
                                             String b_pub, String result) throws Exception {

        NamedParameterSpec paramSpec = new NamedParameterSpec(curveName);
        KeyFactory kf = KeyFactory.getInstance("XDH");
        KeySpec privateSpec = new XECPrivateKeySpec(paramSpec, hexStringToByteArray(a_pri));
        PrivateKey privateKey = kf.generatePrivate(privateSpec);
        boolean clearHighBit = curveName.equals("X25519");
        KeySpec publicSpec = new XECPublicKeySpec(paramSpec, hexStringToBigInteger(clearHighBit, b_pub));
        PublicKey publicKey = kf.generatePublic(publicSpec);

        byte[] encodedPrivateKey = privateKey.getEncoded();
        System.out.println("Encoded private: " + byteArrayToHexString(encodedPrivateKey));
        byte[] encodedPublicKey = publicKey.getEncoded();
        System.out.println("Encoded public: " + byteArrayToHexString(encodedPublicKey));

        KeyAgreement ka = KeyAgreement.getInstance("XDH");
        ka.init(privateKey);
        ka.doPhase(publicKey, true);

        byte[] sharedSecret = ka.generateSecret();
        byte[] expectedResult = hexStringToByteArray(result);
        if (!Arrays.equals(sharedSecret, expectedResult)) {
            throw new RuntimeException("fail: expected=" + result + ", actual="
                    + byteArrayToHexString(sharedSecret));
        }
    }

    public static void main(String[] args) throws Exception {
        runDiffieHellmanTest(
                "X25519",
                "77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a",
                "de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f",
                "4a5d9d5ba4ce2de1728e3bf480350f25e07e21c947d19e3376f09b3c1e161742");
    }
}

You have incorrectly swapped two lines in hexStringToBigInteger:

            if (clearHighBit && i == str.length() / 2 - 1) {
                curVal &= 0x7F;
                result = result.add(BigInteger.valueOf(curVal).shiftLeft(8 * i));
            }

should instead be:

            if (clearHighBit && i == str.length() / 2 - 1) {
                curVal &= 0x7F;
            }
            result = result.add(BigInteger.valueOf(curVal).shiftLeft(8 * i));