com.sun.javafx.scene.control.behavior.KeyBinding.getSpecificity() contains the following code:

    if (code != null && code != event.getCode()) return 0; else s = 1;
    // ...
    if (eventType != null && eventType != event.getEventType()) return 0; else s++;

which means that it does not differentiate between code == null and code == event.getCode(), i.e. returns the same value for both cases, while the latter is more specific. The same is true for eventType.