    @Test
    public void testToHexString() {

        assertEquals("", toHexString(bytes()));
        assertEquals("C5", toHexString(bytes(0xC5)));

        assertEquals("FEDCBA9876543210", toHexString(bytes(
                0xFE, 0xDC, 0xBA, 0x98, 0x76, 0x54, 0x32, 0x10)));
    }