Debug: cart Object
(
    [id] => 2
    [user] => user Object
        (
            [id] => 1
            [firstname] => Michael
            [name] => Haussmann
            [mail] => michael@phpersistence.org
            [telephones] => Array
                (
                    [0] => 04 67 54 55 xx
                    [1] => 06 11 73 43 xx
                )

        )

    [products] => Array
        (
        )

    [date] => 1542565890
)