qmllint: Type "QList<int>" of property "boo" not found

import QtQuick 2.15                                                                                                                                                               
import QtQuick.Window 2.15                                                                                                                                                        
import example.mylib                                                                                                                                                              
                                                                                                                                                                                  
Window {                                                                                                                                                                          
    id: win                                                                                                                                                                       
    width: 640                                                                                                                                                                    
    height: 480                                                                                                                                                                   
    visible: true                                                                                                                                                                 
    title: qsTr("Hello World")                                                                                                                                                    
    property int a: 16                                                                                                                                                            
                                                                                                                                                                                  
    Component.onCompleted: {                                                                                                                                                      
        win.a = myItem.foo + 1;                                                                                                                                                   
        console.log("win.a =", win.a);                                                                                                                                            
    }                                                                                                                                                                             
    MyItem {                                                                                                                                                                      
        id: myItem                                                                                                                                                                
    }                                                                                                                                                                                                                                                                                                 
}                                                                                                                                                                                 

#include <QQuickItem>                                                                                                                                                             
                                                                                                                                                                                  
class MyItem : public QQuickItem                                                                                                                                                  
{                                                                                                                                                                                 
    Q_OBJECT                                                                                                                                                                      
    QML_ELEMENT                                                                                                                                                                   
    Q_PROPERTY(quint32 foo MEMBER foo_ NOTIFY fooChanged FINAL)                                                                                                                   
signals:                                                                                                                                                                          
        void fooChanged();                                                                                                                                                        
public:                                                                                                                                                                           
        MyItem();                                                                                                                                                                 
private:                                                                                                                                                                          
        quint32 foo_ = 17;                                                                                                                                                        
};