QDeclarativePropertyMap::keys() cannot be called from qml

The following code does not work as expected. QML thinks that keys is a property that needs to be added instead of the Q_INVOKABLE function.

QDeclarativePropertyMap *test = new QDeclarativePropertyMap;
test->insert("prop", QVariant(2));
engine()->rootContext()->setContextProperty("test", test);

console.log(test.keys())

This code results in:
TypeError: Result of expression 'test.keys' [undefined] is not a function.

From what I was able to find, the function QDeclarativeOpenMetaObject::createProperty is called with keys, and then the property 'keys' is auto created. As a work around I overloaded the createProperty in QDeclarativePropertyMap and just checked if the created property is 'keys' and return a -1, but its not nice. I just dont know enough about the internals of the script and qml engines to propose a cleaner solution.