Vaadin ComboBox

This could be very basic . I am using vaadin comboBox component and loading values dynamically from a property file like below
application.properties
combo.list.of.Type=one,two,three

and injecting the values using spring @Value annotation
@Value("#{'${combo.list.of.Type}'.split(',')}")
    private List<String> st;

And 
ComboBox testType= new ComboBox("Types");
testType.addItems(st);

the above code works fine. But now I want  to add caption to each of the values like
for combobox item 'one' the display value should be ONE, for 'two' display value should be TWO. anyone knows how to achieve this?

Thanks in advance

-Barath