I'm trying to represent a MenuItem in FXML, and have successfully done so with the exception of the accelerator key:

            MenuItemBuilder.create()
              .text("New...")
              .graphic((new ImageView(
                new Image(getClass().getResourceAsStream("images/paper.png"))))
              )
              .accelerator(KeyCombination.keyCombination("Ctrl+N"))
              .build(),

Feedback from Greg Brown:
Looks like KeyCombination needs a valueOf() method. When a class defines a static valueOf() method, you can do this in FXML:

<KeyCombination fx:value="Ctrl+N"/>

The existing implementation of keyCombination() could delegate to valueOf(), or vice versa, to maintain backward compatibility.