@Test
public void testFindByAge() throws
        Exception {

    final MultiMap<Value, Person, List<Person>> age = map.get(KeyDefinition.newKeyDefinition()
                                                                      .withId("age")
                                                                      .build());
    Util.assertMapContent(age,
                          20,
                          20,
                          30);
    assertTrue(age.get(new Value(20))
                       .contains(toni));
    assertTrue(age.get(new Value(20))
                       .contains(eder));
}