public static String toHex(final byte[] bytes) {
        if (bytes == null) {
            return null;
        }
        final char[] hexChars = new char[bytes.length * 2];
        for (int j = 0; j < bytes.length; j++) {
            int v = bytes[j] & 0xFF;
            hexChars[j * 2] = HEX_ARRAY[v >>> 4];
            hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];
        }
        return new String(hexChars);
    }
@SuppressWarnings("ConstantConditions")
    @Test
    public void testToHex() {
        Assert.assertNull(BytesUtil.toHex(null));

        Assert.assertEquals("0102", BytesUtil.toHex(new byte[] { 1, 2 }));
    }