public static SignatureData signMessage(byte[] message, ECKeyPair keyPair) {
        return signMessage(message, keyPair, true);
    }
@Test
    public void testSignMessage() {
        Sign.SignatureData signatureData =
                Sign.signPrefixedMessage(TEST_MESSAGE, SampleKeys.KEY_PAIR);

        Sign.SignatureData expected =
                new Sign.SignatureData(
                        (byte) 28,
                        Numeric.hexStringToByteArray(
                                "0x0464eee9e2fe1a10ffe48c78b80de1ed8dcf996f3f60955cb2e03cb21903d930"),
                        Numeric.hexStringToByteArray(
                                "0x06624da478b3f862582e85b31c6a21c6cae2eee2bd50f55c93c4faad9d9c8d7f"));

        assertEquals(signatureData, (expected));
    }