qmltypes warning when using const in Q_INVOKABLE

I am exposing MyType to QML via qt_add_qml_module().
I am trying to use const with Q_INVOKABLE like so (this is just a sample code to reproduce the issue):

#ifndef MYTYPE_H
#define MYTYPE_H
#include <QObject>
#include <QQmlEngine>
class MyType : public QObject
{
    Q_OBJECT
    QML_ELEMENT
public:
    explicit MyType(QObject *parent = nullptr)
        : QObject{parent}
    {}
    Q_INVOKABLE const QObject *getObject() const
    {
        const QObject *object = nullptr;
        return object;
    }
};
#endif // MYTYPE_H

I get the following warning at compile time:

Warning: debug\MyApp\appMyAppqmltypes:16:71: Expected only name, type, revision, isPointer, isList, isCloned, isConstructor, and isJavaScriptFunction in script bindings.
 
[import]

Why isConstant cannot be used Method { } in .qmltypes? Am I missing something or it is a bug?