*/
    @Test
    public void testToHex() throws Exception {
        assertEquals("010203", StringUtil.toHex(new byte[] { 1, 2, 3 }));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testToHex2() throws Exception {
        assertEquals("0001", StringUtil.toHex(1));
    }

    /**
     * @throws Exception
     */
    @Test

    }

    /**
     * Converts a byte array to a hexadecimal string.
     *
     * @param bytes
     *            the byte array
     * @return the hexadecimal string
     */
    public static String toHex(final byte[] bytes) {
        if (bytes == null) {
            return "";
        }
        final StringBuilder sb = new StringBuilder(bytes.length * 2);
        for (final byte b : bytes) {