There seems to be a conflict between the following:

1) New MVC namespace syntax:
<mvc:content-negotiation use-not-acceptable="true">
	    	<mvc:default-views>
	      		<bean class="org.springframework.web.servlet.view.JstlView">
	      			<property name="url" value="" />
	      		</bean>
	    	</mvc:default-views>
	  	</mvc:content-negotiation>

2) Inside my Unit test:
ResultActions actions =
this.mockMvc.perform(get("/vets.xml").accept(MediaType.TEXT_XML));
        actions.andDo(print()); // action is logged into the console

        actions.andExpect(status().isOk());