code: public static void assertSingleElement(final Collection<?> collection, final StatusType status) {
  		RESTAssert.assertNotNull(collection, status);
  		RESTAssert.assertTrue(collection.size() == 1, status);
  	}
docs: assert that collection has one element
  
  @param collection the collection to check
  @param status the status code to throw
  @throws WebApplicationException with given status code