Figuring how to to use Multi-select field about swing-extensions HOT 1 CLOSED

MultiSelectField field = MultiSelectField.builder(true, true)
        // prepopulate the field with values
        .items(Arrays.asList("one", "two"))
        // the `tab` key switches focus instead inputing a character
        .disableTab()
        // validate pending items (e.g. only allow unique values)
        .pendingItemValidator((input, text) -> input.getItems().indexOf(text) == input.getItems().size()-1)
        // don't add the pending item when focus changes
        .setKeepTextOnFocusLost(true)
        // don't allow focus change with an invalid pending item
        .setYieldFocusOnError(false)
        .get();

ValidatedMultiSelectField field = MultiSelectField.builder(true, true)
        // validate the list (e.g. require minimum input)
        .validator(items -> items.size() < 2 ? "Need at least 2 values" : null)
        .get();

JScrollPane scrollPane = new JScrollPane(field);
ValidationBorder.addToViewport(field);
JFrame frame = new JFrame("test");
frame.getContentPane().setLayout(new BorderLayout());
frame.getContentPane().add(scrollPane, BorderLayout.CENTER);
frame.pack();
frame.setSize(400, 100);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setVisible(true);