Do you need AJAX? If you only have 3 projects, it would be much easier to populate an associative array and select the entries in it when the project name is selected.
If you do want to go the AJAX route,
you should be aware that the Struts Dojo integration was
deprecated in Struts 2.1 (I don't know why they don't make that more obvious in the documentation). I believe the Dojo plugin is an ancient version of Dojo kept around only so existing applications that depend on the AJAX tags will not break.
I recommend the
Struts 2 jQuery Plugin for the most up-to-date AJAX tools.
That said, what specific questions do you have?