public MultiMap<Value, T, List<T>> get(final KeyDefinition keyDefinition) {
        return tree.get(keyDefinition);
    }
@Test
    void testFindByAge() throws Exception {
        final MultiMap<Value, Person, List<Person>> age = map.get(KeyDefinition.newKeyDefinition()
                .withId("age")
                .build());
        
        assertThat(age.keySet()).extracting(x -> x.getComparable()).containsExactly(20, 30);
		
        assertThat(age.get(new Value(20))).contains(toni, eder);
    }