assert statement in junit for Map object

@RunWith(SpringJUnit4ClassRunner.class)

@ContextConfiguration(classes=DifConfig.class, loader=AnnotationConfigContextLoader.class)
public class TestVendor {

	private Logger logger=Logger.getLogger(VendorService.class);

	@Inject
	transient private VendorService vendorService;
	@Test
	public void testVendorList() {

		Map<String, String> vendorList = vendorService.getVendorList();
		
	}
            

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>>Map<String, String> vendorList = vendorService.getVendorList();


what kind of Assert statment i can write around above map object(vendorList ) which comes as result of get method call(getVendorList) on business service class(vendorService)

please advise
Any links resources ideas highly appreciated. Thanks in advance