QML_CONSTRUCTIBLE_VALUE misbehaves on constructors taking QJSValue

class VARIANT
{
    Q_GADGET
    QML_VALUE_TYPE(variant)
    QML_CONSTRUCTIBLE_VALUE
    Q_PROPERTY(QDBusVariant value READ getValue)
public:
    explicit VARIANT()
    {
    }
    Q_INVOKABLE explicit VARIANT(const QJSValue &_value)
        : value(_value.toVariant())
    {
        qDebug() << Q_FUNC_INFO << value.variant() << _value.toString();
    }
    operator QVariant() const
    {
        return value.variant();
    }
    operator QDBusVariant() const
    {
        return value;
    }
    Q_INVOKABLE QString toString() const
    {
        return value.variant().toString();
    }

    QDBusVariant getValue() const
    {
        return value;
    }

    QDBusVariant value;
    constexpr static const char *signature = "v";
};

import QtQml
import varianttype as DBus

QtObject {
    property DBus.variant test: "abcdefg"
}

Could not find any constructor for value type VARIANT to call with value QVariant(QString, abcdefg)
QQmlApplicationEngine failed to create component
qrc:/qt/qml/varianttype/Main.qml:5:27: Cannot assign value abcdefg to property test