I tested with latest Vaadin 24.4.alpha22 (using "Create project" from install menu and changing version), but can’t get anything to screen.
xterm = new XTerm();
add(xterm);
xterm.writeln("Hello world.\n\n");
xterm.setCursorBlink(true);
xterm.setCursorStyle(ITerminalOptions.CursorStyle.UNDERLINE);
xterm.setSizeFull();
xterm.addLineListener(e -> {
String input = e.getLine();
Notification.show(input);
});