Some accessors in QDeclarativeView are const and other non const without a evident reason for it

In QDeclarativeView you have

QDeclarativeEngine * engine ()
Returns a pointer to the QDeclarativeEngine used for instantiating QML Components.

QDeclarativeContext * rootContext ()
This function returns the root of the context hierarchy. Each QML component is instantiated in a QDeclarativeContext. QDeclarativeContext's are essential for passing data to QML components. In QML, contexts are arranged hierarchically and this hierarchy is managed by the QDeclarativeEngine.

QGraphicsObject * rootObject () const
Returns the view's root item.

All three return a pointer and reading the documentation one thinks all of them are just accessors so it would make sense for all three to be const, in case the two that are not const really modify the object it would be good if that was documented