Triggered action procedures take an ActionEvent as defined in the ActionListener interface. Unfortunately the jline code always passes null in place of an event. This completely violates the purpose of having an event, which is to give the event handler information about how it was invoked.
Even though jline is not like AWT (where the ActionListener interface came from), a jline action procedure may want to know the keystroke that triggered it. Consider the case when the same procedure is triggered by more than one keystroke.