public MultiMap<Value, T, List<T>> get(final KeyDefinition keyDefinition) {
        return tree.get(keyDefinition);
    }
@Test
    void testFindByUUID() throws Exception {
    	assertThat(map.get(UUIDKey.UNIQUE_UUID).keySet()).containsExactlyInAnyOrder(toni.uuidKey.getSingleValue(),
    			eder.uuidKey.getSingleValue(),
                michael.uuidKey.getSingleValue());
    }