@Override
    public void setCommandLineListener(final AceCommandLineListener listener) {
        textBox.addKeyDownHandler(event -> {
            if (event.getNativeKeyCode() == KeyCodes.KEY_ENTER) {
                event.preventDefault();
                listener.onCommandEntered(textBox.getValue());
            }
        });
    }
Set listener getting callback from command line component.
Typically editor registers listener itself.

@param listener listener for command entering event
stroom-core-client-widget/src/main/java/edu/ycp/cs/dh/acegwt/client/ace/AceDefaultCommandLine.java