@Test
void get_whenMultipleValuesForGroup_thenReturnCorrectAggregation() {

    ImmutableSet<TestState> states = ImmutableSet.of(
            new TestState(Id.create(1), CoordinateLikeTestObject.ORIGIN, 1),
            new TestState(Id.create(2), CoordinateLikeTestObject.ORIGIN, 3),
            new TestState(Id.create(3), CoordinateLikeTestObject.ORIGIN, 5));
    cache.addAll(states);
    assertThat(groupByAggregation.get(CoordinateLikeTestObject.ORIGIN)).isEqualTo(9);
}