Unclear how to use addKeyDown/Up/PressListener

KeyNotifier.addKeyDownListener(String key, ComponentEventListener<KeyDownEvent> listener, KeyModifier... modifiers) javadoc says

Adds a {@code keydown} listener to this component, conditional on key and modifiers.
key: the key to match

What remains unclear is:

• Why is the key a String? What happens with addKeyDownListener("abc",...)?
• How do I listen to enter? Debugging shows that I should use “Enter” as they key to match, which was quite unexpected. Especially as “enter” does not work. There is seemingly no way to know upfront if I should use esc, Esc, escape or Escape to match the escape key

I would have expected the key parameter to be a a character and 13 would listen to enter

[heruan]

@knoobie and @Legioth suggestions in #4061, plus improved JavaDocs.

[Legioth]

The benefit would be discoverability, i.e. that your IDE will offer better auto complete suggestions.

As an alternative to an enum, I would suggest an interface with constants and a static of(String) factory method for other cases. The code would thus look like this instead:

1. addKeyPressListener(Key.ENTER, ...)
2. addKeyPressListener(Key.of("ö"), ...)

Another alternative would be to have two separate overloads of addKeyPressListener (and all other similar methods), one accepting Key enum values and one accepting strings. This would again help the IDE guide users to the predefined Key.XYZ values.