The generic type is not showing in the JavaDoc for these classes because the angle brackets are not escaped. For example in BeanModel the HTML source is

private List<NumberTag> numbers;

-

com.extjs.gxt.ui.client.data.BeanModel:
private List numbers;


com.extjs.gxt.ui.client.widget.form.NumberField:
NumberField field = new NumberField;

com.extjs.gxt.ui.client.widget.form.SimpleComboBox:
SimpleComboBox combo = new SimpleComboBox();