Change DefaultConversionService to FacesConversionService in Spring webflow test

Currently I'm writing tests for Spring web flow.

In tested flow I've got result-type="dataModel". I've figured out that Spring is using DefaultConversionService for this test and does not have alias dataModel. With DefaultConversionService test can not pass. I've changed dataModel to javax.faces.model.DataModel and it works, but it's not what I want.

So my question is how can I tell Spring to use FacesConversionService (added "dataModel" alias) which extends DefaultConversionService?