Problem in compilation with custom metatype

[ada10]

I have a custom metatype declared as shown below -

class thumbnaildata : public QObject
{
    Q_OBJECT
 
public:
    thumbnaildata();    //default ctor
    thumbnaildata( QPixmap aPixmap,QString aPmapFilePath ); //ctor with parameters
    thumbnaildata( const thumbnaildata& other );            //mandatory copy ctor
 
    ~thumbnaildata();
 
    void setPixmap( QPixmap aPixmap );
    void setFilePath( QString aPmapFilePath );
 
    QPixmap getPmap();
    QString getPmapFilePath();
 
private:
    QPixmap mMypixmap;
    QString mPixmapFilePath;
 
};
 
Q_DECLARE_METATYPE( thumbnaildata )

class thumbnaildata : public QObject
{
    Q_OBJECT

public:
    thumbnaildata();    //default ctor
    thumbnaildata( QPixmap aPixmap,QString aPmapFilePath ); //ctor with parameters
    thumbnaildata( const thumbnaildata& other );            //mandatory copy ctor
    
    ~thumbnaildata();
    
    void setPixmap( QPixmap aPixmap );
    void setFilePath( QString aPmapFilePath );
    
    QPixmap getPmap();
    QString getPmapFilePath();

private:
    QPixmap mMypixmap;
    QString mPixmapFilePath;
    
};

Q_DECLARE_METATYPE( thumbnaildata )

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When I compile this definition & use it in a model class ( compatible with QVariant ), I am getting the following error -

" Error: #145: member "thumbnaildata::staticMetaObject" may not be initialized
const QMetaObject thumbnaildata::staticMetaObject = { "

What is the issue & has anyone faced this issue before ?