character property Null safety
The character of the triggering event.
This is typically a single-character string, such as '?' or 'œ', although
CharacterActivator doesn't check the length of character or whether it
can be matched by any key combination at all. It is case-sensitive, since
the character is directly compared by
== to the character reported by
- RawKeyEvent.character, the character of a key event.
final String character;