How can I update the Codename One libraries?

I tried and tried to run this code in a new "bare bones" project, but there is nothing to do, it always gives me the following error:

/home/francesco/NetBeansProjects/TestUUID/src/net/informaticalibera/test/UUID/MyApplication.java:62: error: cannot find symbol
                hi.add(new SpanLabel(Util.getUIID()));
  symbol:   method getUIID()
  location: class Util
1 error

Code that is known to work, it's an example that I inserted in the Javadoc of Util.getUIID:

        Form hi = new Form("Test UIID", BoxLayout.y());
        Button button = new Button("Generate 10 UIID");
        hi.add(button);
        hi.show();
        button.addActionListener(l -> {
            String myId = "myUsername"; // do not exceed 12 characters
            Preferences.set("CustomDeviceId__$", Long.parseLong(myId, 36));
            hi.add(new SpanLabel("10 Random UUID"));
            for (int i = 0; i < 10; i++) {
                hi.add(new SpanLabel(Util.getUIID()));
            }
            hi.revalidate();
        });

I think it is a problem of updating the Codename One libraries, which maybe in a project bare bones are old. However, opening "Codename One Settings", clicking on the hamburger menu at the top right and choosing first "Update" and then "Save" I keep getting the same error. If I try to use the old version of the "Codename One Settings" GUI, clicking on "Basic" and then "Update Project Libs", the problem remains. I don't know what to do.

Is it a Codename One bug or am I not doing the right action?