[REVIEW] Make controller instantiation customizable

[Greg Brown]

>>> <param fx:id="someParameterInTheNamedParametersMap" />

> I need a couple days to really think about it. The basic idea is that it provides an alternative way to populate the FXML namespace with things that could be referenced. So for example instead of having to add properties to a controller that your FXML then binds to, you could just create a <param> for elements in your namespace map provided on the FXML loader and then you could reference those from elsewhere in the document.

I'm afraid I still don't completely understand. Could you provide a concrete example?

>> It would be consistent with other unrelated parts of the platform, but not with the BuilderFactory interface, which is used by FXMLLoader and is already defined similarly to ControllerFactory.
> 
> The difference is that BuilderFactory is intended to be implemented by random code. That is, every Builder in existence is supposed to implement it.

I think you may be thinking of Builder, rather than BuilderFactory. BuilderFactory defines a single getBuilder() method, like ControllerFactory's getController().