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

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