QVariant<QStringList>: toString() return an empty string

I think the method documentation is wrong :

Returns the variant as a QString if the variant has userType() QMetaType::QString, QMetaType::Bool, QMetaType::QByteArray, QMetaType::QChar, QMetaType::QDate, QMetaType::QDateTime, QMetaType::Double, QMetaType::Int, QMetaType::LongLong, QMetaType::QStringList, QMetaType::QTime, QMetaType::UInt, or QMetaType::ULongLong; otherwise returns an empty string.

We have to use QStringList.join() and assume a separator to cast a QStringList to QString.