import QtQuick 2.0

Item {
    component Base : Item {
        required property string required_now_string
        property string required_later_string
        property string required_even_later_string
    }

    component Derived : Base {
        required required_later_string
    }

    Derived {
       required required_even_later_string
       required_now_string: ""
    }
}