Suggestion

        for (String wordKey : oldSO.keySet()) {
            if (!newSO.containsKey(wordKey)) {
                newSO.put(wordKey, oldSO.get(wordKey));
            } else {
                SemanticOccurance so = new SemanticOccurance();
                so.setCount(newSO.get(wordKey).getCount() + oldSO.get(wordKey).getCount());
                newSO.put(wordKey, so);
            }
        }