@Override
    public Object merge(T mergingValue, T existingValue) {
        if (mergingValue == null) {
            return existingValue.getRawValue();
        }
        return mergingValue.getRawValue();
    }
@Test
    public void merge_mergingNotNull() {
        MapMergeTypes existing = mergingValueWithGivenValue(EXISTING);
        MapMergeTypes merging = mergingValueWithGivenValue(MERGING);

        assertEquals(MERGING, mergePolicy.merge(merging, existing));
    }