@Test
public void testMathExpression() throws Exception {
Literal literal = ff.literal(new Integer(2));
Multiply mathExp = ff.multiply(ff.property("measurement/result"), literal);
List unrolledExpressions = (List) mathExp.accept(visitor, null);
assertEquals(1, unrolledExpressions.size());
Expression unmapped = (Expression) unrolledExpressions.get(0);
assertTrue(unmapped instanceof Multiply);
Multiply mathUnmapped = (Multiply) unmapped;